STEUCTUEAL DEAFTING 



A PRACTICAL PRESENTATION OF DRAFTING AND DETAILING 

METHODS USED IN DRAWING UP SPECIFICATIONS FOR 

STRUCTURAL STEEL WORK 



By FRANK O. DUFOUR, C. E. 

ASSISTANT PROFESSOR OF STRUCTURAL ENGINEERINa, 
UNIVERSITY OF ILLINOIS 



ILLUSTRATED 



AMERICAN TECHNICAL SOCIETY 

CHICAGO 

1921 






COPYRIGHT, 1912. 1913, 1914. 1920. B^ 
AMERICAN TECHNICAL SOCIETY 



COPYRIGHTED IN GREAT BRITAIN 
ALL RIGHTS RESERVED 



OEC H 1920 
©CI.A601769 



CONTENTS 



PAGE 



Drafting room equipment and practice 1 

Classification of drawings 1 

Drafting — room personnel 2 

Assignment of work . 3 

Records 4 

Drafting materials 6 

Stress sheet 11 

Layout 12 

Allowances for planing and cutting 15 

Allowances for pin material 15 

Allowances for bending 16 

Shop bills 17 

Detailing — General instructions 35 

Lettering . 35 

Abbreviations 39 

Dimension and material notation 40 

Rivets and rivet spacing 45 

Bolts, nuts, and washers 54 

Tension members :T. ... 57 

Clearances 59 

Detailing methods 65 

Detailing of angles 65 

Detailing of plates 66 

Detailing of combinations of structural shapes 71 

Detaihng of beams. 72 

Detailing of roof trusses 81 

Detailing of plate girder spans 87 

Detailing of compression members Ill 

Detailing of built-up tension members 112 

Facilitation of erection 112 




-^,|;:> «*<llgi 




WOOLWORTH BUILDING IN PROCESS OF CONSTRUCTION 

Cass Gilbert, Architect 
Courtesy of Thompson-Starrett Company, ISlSWVOYk Citif 



INTRODUCTION 

A STEEL skyscraper, like the fifty-five story Woolworth Build- 
ing in New York, is an architectural and engineering triumph 
and its erection is a never-ending source of interest and wonder 
to the spectator. Throngs of interested persons are always 
standing near while the giant derricks raise the columns and 
girders aloft, swing them into place, and leave them to be fastened 
securely by the men with white hot rivets and pneumatic hammers. 
And yet in all the confusion of noise and bustle of the workmen, 
the control of the engineer with the blue detail sheets before him 
is in evidence. Every piece of steel has a certain place in that 
great structure and, although made miles from the scene and 
possibly in different mills, every piece fits exactly down to the 
rivet holes. The skeleton grows before your eyes, a potent illus- 
tration of the might of minds, of the value of accuracy of detail 
and organization of mechanical forces. 

^ Do we not too often, in the midst of our wonder and apprecia- 
tion of this marvelous work of man, forget from whence all this 
order and system sprang? Do we not lose sight of the careful 
calculation of the size and thickness of every angle, plate, and 
girder, the location of the holes, and the number and size of the 
rivets to be used? When we think also of the checking and recheck- 
ing of all the calculated results in order to avoid mistakes in dimen- 
sions and in order to make sure that no structural member is to 
be called upon to bear strains beyond its strength, we begin to 
see how it is possible for a whole building to be put together without 
one alteration^ without one single piece being sent back to the mill. 
The man who stands boldly on a swinging girder and looks down 
from dizzy heights to the throng below is a very unimportant 



INTRODUCTION 

man compared to the designer, the detail man, the checker, and 
the steel mills' superintendent, who carry the work safely and 
accm-ately to a finish. 

^ The author in this article has spoken from a ^^'ide experience 
in this line of work and his practical instructions regarding drafting 
methods, systems of costs, record sheets, and the detailing of the 
elements of structural steel will be found of exceptional value to 
every trained and untrained man. It is the hope of the pub- 
lishers that the work vdW be of ser\'ice to a wide circle of students 
and general readers. 




HOTEL LASALLE, CHICAGO \ 

Holahird and Roche, Chicago, Architects. George A. Fuller Company, Contractors, Chicago 




BLACKSTONE HOTEL, CHICAGO, IN PROCESS OF CONSTRUCTION ^ 

'^^'/^^'''fPj^^?^ I^°*^LJ^ °^ ^^^^ ^^^ Tile Construction Throughout, with Brick Exturior 
Marshall & Fox, Chicago, Architects. Geo. A. Fuller Company oTneralcSntraf^^^^^^^ 



STRUCTURAL DRAFTING 

PART I 



DRAFTING ROOM EQUIPMENT AND PRACTICE 

Introduction. Structural drafting may be defined as the art 
of making drawings of certain objects and placing thereon dimen- 
sions and other notes which when taken together will convey the 
necessary information for the manufacture and in some cases the 
erection of the structure under consideration. 

In the making of these drawings great accuracy in drafting 
is not necessarily required. The chief requisites are that the letter- 
ing and dimensions should be so clear that no misunderstanding 
is possible. Dimensions not given should never be scaled by the 
draftsman or workman, but the actual value should be ascertained 
by consulting some one familiar with the work. 

Classification of Drawings. The classes of drawings which are 
made in a structural drafting room are: the stress sheet; the assem- 
bly, or general detailed, drawings; and the shop drawings, or, as 
they are more often called, the detailed drawings. 

The stress sheet is a tracing upon which is usually shown a 
skeleton outline of the structure upon the lines of which are marked 
the stresses which are caused by the traffic or other forces to which 
the structure is subjected, and also the size and shape of the mem- 
ber designed to withstand these stresses. 

The assembly or general detailed drawings usually give several 
views of the structure as it appears after it has been erected. On 
these views are shown to scale the members as they appear in the 
finished structure together with all the rivets and other details 
necessary for its completion. The overall dimensions are usually 
given and also any other dimensions which are necessary for the 
draftsman to complete the shop drawings. While the size of the 
members and their connections, as well as the number of rivets 



2 STRUCTURAL DRAFTING 

required, are always given, yet in a few cases the length of the member 
or shape and the individual spacing of the rivets are also given. 

The shop drawings, or detailed drawings as they are more 
often called, consist of views of a certain member of the finished 
structure so dimensioned that it may be constructed by the men in 
the shop. It requires greater skill and more experience to make 
the assembly drawings than it does the detailed drawings, but in 
each case the men must be familiar not only with the drafting prac- 
tice but also with that of the mill and the shop. 

Drafting=Room Personnel. A drafting-room force consists of 
an engineer, a chief draftsman, squad boss, checkers, draftsmen, 
and tracers. 

The engineer has charge of the plant as well as of the drafting 
room and is directly responsible for the ordering of all material, 
the manufacturing of the structure and its shipping to the place of 
erection. He conducts the correspondence, keeps track of the work 
in the drafting room and in the shop, and, in case his plant is one 
of many of a large corporation, makes weekly or monthly reports 
to his superior ofiicers. In case his plant is a small one, the en- 
gineer usually does most of the work of designing and estimating. 

The chief draftsvian is directly responsible to the engineer for 
the getting out of the detailed plans or shop drawings and also 
ordering of the material. 

The squad boss reports to the chief draftsman and his duty is 
to keep track of and to get out the drawings of any particular struc- 
ture which is assigned to him by the chief draftsman. The squad 
bosses usually have from three to four to as many as twenty drafts- 
men under them, according to the magnitude or the number of 
structures which they are responsible for. 

In addition to the draftsmen are the checkers, certain men 
usually of great experience in matters relative to mill and shop as 
well as drafting-room practice. It is the duty of these checkers 
to go over the draftsmen's work, see that all errors are corrected, 
and then finally sign it as approved. The checker only is held re- 
sponsible for mistakes which then may be left upon the sheet. 

The tracers are for the most part young college graduates or 
apprentices, and their office is simply to trace the drawings which 
are handed to them bv the draftsmen. 



STRUCTURAL DRAFTING 3 

A fireproof vault is always a part of the equipment of every 
well-equipped drafting office. In it are kept the notebooks in 
which the computations necessary for the design and detailing of 
the structures are kept, and also the tracings which have been made 
in the drafting room. In case the drawing of any particular structure 
is required, the tracing is taken out of the vault, blue prints are made, 
and the tracing returned as soon as possible. The vault should be 
so equipped that whenever the door is opened the interior becomes 
lighted. Aside from the mechanical convenience of this arrange- 
ment, it avoids the possibility of any person being accidentally 
locked in, since the rule is that in case of fire the vault should be 
immediately closed by the one nearest to it. 

Assignment of Work. When the engineer of the plant received 
a stress sheet from his head officer or from the designing depart- 
ment in his own work, he hands it to the chief draftsman. The 
chief draftsman makes a record of it and gives it to the squad boss 
who is most accustomed to that class of work. The squad boss in 
turn hands it to the checker or checkers and these men make details 
for the various parts of the structure and make layouts for the 
various joints. The engineer now orders the material which will 
be required to build the structure or assigns a checker to do so and 
then returns the stress sheet to the squad boss who assigns certain 
draftsmen to prepare the shop drawings for the structure. Draftsmen 
make the drawings and turn them over to the tracers to trace them. 

After the tracer has finished the tracings of the sheets, he passes 
them to the checker who in the first place made out the details and 
layout and ordered the material. The checker goes over these trac- 
ings very carefully and sees that all dimensions are correct, that 
all material used is that which he ordered, and if the drawings are 
correct he signs his name to the sheet. If the dimensions or any 
other matter upon the drawing is found to be incorrect, the checker 
places a ring around it with his blue pencil which is used in check- 
ing and off to one side places the correct value. After all the apparent 
errors have been corrected in this manner, a consultation between the 
checker and the draftsman who made the drawing is held. The errors 
are pointed out to the draftsman who in turn checks the work to 
prove the checker's results. The draftsman then takes the drawing 
and makes the necessary changes and returns it to the checker. 



4 STRUCTURAL DRAFTING 

Great care should be taken in making the changes that no 
dimensions or other notations written upon the drawing by the 
checker are rubbed off. The checker then examines the drawing 
carefidly to see that all the errors which he has pointed out have 
been corrected. He then cleans the tracing, signs his name to it, 
and retiu-ns it to the squad boss. The squad boss in turn has the 
necessary blue prints made and tiu-ns the tracing together 'with 
the prints over to the chief draftsman, who in turn files the tracing 
in its proper place and gives the blue prints to the engineer of the 
plant who sees that they are distributed to the foremen of the various 
shops where they are required. 

Records. A job is known by the order number which is given 
it when it comes into the hands of the engineer of the plant. This 
order nimiber should go on all papers upon which am-thing con- 
cerning that structiu^ is placed. Failure to do this will result in 
great confusion and much time will be lost. The penalty for persist- 
ent failiu-e to c-omply with this ver\' important method of procedure 
is usually dismissal. 

Since the draftsman, or in fact any of the office force, may 
work upon more than one order during the day or week, and since 
it is important that the cost of the drafting or engineering work for 
any particular order shoidd be known, it is essential that the men 
keep time cards upon which the order and the time placed upon that 
order is noted. Usually fractions of an hoiu* less than one-fourth 
are not reported. Fig. 1 shows one of these time cards upon which 
is noted the work of a checker for one week. It shows that he has 
worked upon several orders and also shows the exact amount of 
time he has placed upon each one and also the rate per hour which 
he received. In this way it is possible to obtain the cost of engineer- 
ing of any particular order when it has finally been finished. 

An orderly record of the passage of the work from the time the 
stress sheet enters the engineer's office imtil the material has been 
shipped; and also a record of the progress of the work during erection, 
should be kept. This is usually kept on 3X5 cards in the engineer's 
office. In addition to this card-index record, a monthly report in 
blue print form is kept showing the progress of the various orders. 
For instance, the progress report would contain such items as these: 
Order received, layouts made, material ordered, detailed sheets 



rORM » e t53-20M-IO-a2-03 

ENGINEERING DEPARTMENT 
NAME.. J.A.fr.o.sL _ 


RATE....^^. 


TIME CARD FOR WEEK. ENDIKG .../lM..qiJJ..L 


./J .A 


ORDER 




c 
o 


0) 

^2 


1 


3 




■15 
en 


c 

(n 




^2 






L- 


to 


TOTAL 
HOURS 


COST 


Number 


Div. 


B4/F^ 






6 


4 


5^ 


^ 


5 


















25^ 




B4I5^ 






5^ 


4' 


6 


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3i 


















25^ 




























































































































































































































































































































































































































































































































Estimatinq 


































General 


































Holiday 


































Total 




11^ 


<^' 


¥ 


(? 


4 


















51 




Sick 














4 
















4 




Vacation • 


































Out 


































Total 




11^ 


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4 


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¥ 


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55 




HOURS WORKED . . -^ 


/ 




" ALLOWED Cnot 




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«* PAID FO 


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Fig. 1. Draftsman's Time Card Showing Hours Spent on Order Indicated 



6 STRUCTURAL DRAFTING 

finished, shop bills made, templet work finished, work fabricated, 
work shipped; and in addition to this progress report, which is 
made cut in the office, is the report of the erector on a job in the 




Fig. 2. Side View of Drawing Board, Fxaving Elevating Pegs 

field. The erector's form of report contains such headings as tend 
to indicate the progress in the false work; the erection of the trusses 
and floor system; and the amount of field riveting and painting 
completed. 

Drafting Materials. Instruments. The drafting instruments 
required are : A drawing board, T-square, triangles of various kinds 
as noted below, pencils, scales, erasers and erasing shields, a set of 
dramng instruments, a large linen cover, and half sleeves. 

The drawing board should be made of soft pine with battens 
upon the back in order to prevent the warping of the board. Since 
few drawings in structural engineering are larger than 24X 36 inches, 
it is not necessary to have the drafting board larger than 26X38 




Fig. 3. 45° Triangle with Cope and Beam Bevels 

inches. A drafting board should not lie close to a table, but should- 
be raised from the table by small legs placed at its upper edge as 
indicated in Fig. 2. 

The T-square should be about 40 inches in length and should 
be of good quality with an amber edge upon each side. The amber 



STRUCTURAL DRAFTING 7 

edge is of great advantage since it will allow the draftsman to see 
lines below that one which he is drawing and, therefore, prevent 
him from overrunning by drawing one line past its limiting point. 
Such a T-square may be procured for about $2.25. 

The triangles should be of amber or celluloid, and should con- 
sist of the following: One 45-degree triangle with 10- or 12-inch 
sides; one smaller, say with 6-inch sides; two 60-degree triangles 
with 10-inch sides; and two with 4-inch sides. One or more of these 
triangles should have the beam and coping bevels fixed upon it as in 
Fig. 3; this will have to be done by the draftsman, since no such 
triangles are on the market. 

The pencils used by the draftsman should be such as will make 
clear and black lines upon paper in case the drawing is to be traced. 
If the drawing is not to be traced, a harder pencil will suffice. In 
case a drawing is made directly upon tracing cloth, a soft pencil 
should be used and it should be kept sharpened. This Tvill neces- 
sitate frequent rubbing over the sand paper pad which every drafts- 
man should have close at hand in order to keep a good point upon 
his pencil. The pencil recommended for detailing where a tracing 
is to be made is ''Koh-I-Noor, 3 H," although some draftsmen 
prefer 4 H or 5 H. The latter are, in the writer's opinion, to be 
recommended for detailing where a tracing is not required from the 
original. In case drafting is done directly upon tracing cloth, a 
2 H pencil is the correct one to use. 

A red pencil should be kept for marking upon blue prints and 
a blue pencil for making checks on tracings. Never use a red pencil 
upon tracing cloth, since it will not be easy to erase, whereas the 
blue-pencil mark may be washed off with gasoline or erased with a 
pencil eraser. 

The scales required are the architect's and the engineer's. The 
former has certain divisions upon it and each of these divisions is 
divided into twelve parts which indicate inches, and these parts are 
in turn divided into halves or quarters or other small divisions 
denoting the fraction of the inch. The architect's scale which best 
serves the purpose is the one which has the 2-inch, IJ-inch, 1-inch 
§-inch, f-inch, f-inch, J-inch, |-inch, ^-inch, and ^-inch scale. 
A special scale for the making of drawings to a large size or for the 
making of layouts is a great convenience. Such a scale is on the 



8 STRUCTURAL DRAFTING 

market and is divided so that half of an inch is equal to one inch. 
This scale should be in the outfit of all checkers. The engineer's 
scale is one on which the inches are divided into certain decimal 
divisions. The best scale for this is that which has its edges divided 
into 10, 20, 40, 50, and 60 parts of an inch. This scale is of use 
only in laying off bevels and natural functions of angles or in draw- 
ing outlines upon which details will be constructed with the use of 
the architect's scales. The tendency of young engineers to use the 
engineer's scale, allowing a certain decimal to equal a certain fraction 
of an inch, is to be discouraged because of the liability of error, and 
a severe penalty imposed for a second offense. Care should be taken 
in the use of scales such as the architect's which have different 
scales on the same edge in order not to get the feet which belong to 
the ^Tong scale. 

A small paper clamp should be attached to the scale a short 
distance from the center opposite the end where the scale which the 




Fig. 4. Triangular Boxwood Scale, with Scale Guard or Clamp in Position 

draftsman is using is situated. This will prevent the scale from 
being turned over, hence avoiding any other scale, but the one the 
draftsman is using at the time, turning up. Also when the draftsman 
picks up the scale by the paper clamp, the end on which the scale 
he is using is situated -^-ill tilt downward and at once indicate to 
him which end he should place in position to measure what he 
wishes. Fig. 4 shows one of these clamps in position for the scale as 
indicated. 

A good ink eraser, together with a metal sheet called an eraser 
shield in which are various shaped holes, is an indispensable adjimct 
of the draftsman. In all cases where it is necessary to erase, the 
ink eraser and the shield should be used. Never use a knife to erase 



STRUCTURAL DRAFTING 9 

either upon a paper or upon a tracing cloth, for no matter how sharp 
the knife is, the sheet will be rubbed and ink will not run smoothly 
upon the place so worked over. A good soft rubber may be used 
for erasing pencil marks upon either the paper or the tracing cloth, 
although benzine, turpentine, or gasoline is much better for erasing 
pencil marks and cleaning off other dirty spots on the tracing cloth. 
Care should be taken to investigate the status of the insurance and 
fire laws on this point, since in many cases it is not allowable to use 
such inflammable materials in houses of the character of the draft- 
ing office. 

An expensive set of instruments is not necessary in order to 
do good drafting. A good pen, a bow pen, a pair of dividers, and a 
compass with pencil and pen point, are all that are necessary. In 
many cases it is advisable to have two or more pens, one of which 
should be quite large, one medium, and one rather small. 

Many good drafting inks are sold in the open market, and 
it is no longer necessary for the draftsman to make his own ink by 
combining India ink with water. In fact this is a distinct disad- 
vantage, since many of the drafting inks on the market are water- 
proof and while tracings should not be placed so as to become wet, 
nevertheless it is quite an advantage to use waterproof ink upon 
them, so that in case they should be accidentally wetted, it will 
not injure them so that they can not be used. 

A sheet of cambric of dark color the size of the drafting board 
or better still the size of the entire table and drafting board should 
be used to cover up the work when no one is working, since dust 
accumulates very readily upon the drafting board and produces 
much undesirable dirt and, therefore, a very dirty drawing. It is 
also advisable upon starting work in the morning to brush off the 
desk and drawing board and to wipe off the T-square and triangles 
with a cloth. This will prevent dirty marks appearing on the draw- 
ing when they are first placed upon them. 

Detail Paper. Detail paper is the paper upon which a drawing 
is made before it is traced~or upon which drawings are made to be 
used by the detailers in making up the details of the structure. Detail 
papers should be of buff color in order to prevent the showing of dirt 
upon them too easily, and also to be restful to the eye, and they 
should present a surface which will take a pencil or ink mark equally 



10 



STRUCTURAL DRAFTING 



well, and they should not be so thin that they will not stand a great 
amount of erasing. 

]\Iany good papers may be bought in the open market. They 
may be purchased in sheets of a desired size or they may be purchased 
in rolls of a certain weight, and any width. When sold in sheet form 
they are usually sold by number of sheets; when sold in roll form, 
by weight. An inspection of the trade catalogue or letters of inquiry 
to any of the manufacturing concerns will bring further information 
if desired. 

The standard size of a detailed sheet is 24X3G inches. Inside 
of this are drawn two borders each J inch from the other. In the 





.-l^l 








-1^1 










3e" 




ii" 




3^" A 


I 








5i 




















^^^ 


1 






^lOJ 




, 



Fig. 5. Standard Detail Sheet with Dimensions 



lower right-hand corner is the place for the title. The size of this 
block is 4X 5i inches. The 24X 36-inch size is the outside dimension 
of the brown paper or detailed sheet. The 23X35 inch, which is the 
size of the first border line, is the line upon which the blue prints 
are cut. The second border line is the real border line of the draw- 
ing, and remains upon the blue print. Fig. 5 indicates the dimensions 
indicated above. 

Tracing Cloth. Tracing cloth is used on account of the fact that 
the prints may be made from it and, therefore, any number of 



STRUCTURAL DRAFTING 11 

duplicate copies may- be made available for distribution to the 
various departments. The drawings should be made upon the 
rough side of the cloth since this takes the pencil mark and also the 
ink better than does the smooth side. The rough side is also of a 
great ad\^antage when it comes to reproducing the figure by photog- 
raphy. In order to make the ink take readily upon the tracing 
cloth and flow easily, the cloth should first be cleaned by rubbing 
over with powdered chalk or wiping it oft' with gasoline. This removes 
all trace of grease. Before placing the tracing cloth upon the draw- 
ing, the pink border or edge which appears upon the cloth should 
be torn off. If this is not done the sheet will be affected unevenly 
by changes in temperature, and dampness will cause the cloth to 
^^Tinkle up on account of the fact that the border is not affected by 
dampness and the remainder of the cloth is. This mil make it 
difficult for the draftsman to complete his drawing in good form 
in case he has let it lay over for a considerable time, since the lines 
which he made at first will be moved from their original position 
by the wrinkled condition of the sheet. In case it has been forgotten 
to tear off this border and the sheet becomes wrinkled it is advis- 
able to tear off the border and leave the sheet until it becomes straight- 
ened out before further drafting is done. 

In some cases tracing paper is used in making small unimpor- 
tant drawings. This paper should be of good quality in order that 
it may stand erasing, since mistakes are liable to occur and these 
must necessarily be corrected. The best tracing paper is brittle 
and will not stand much handling. For this reason its use for 
expensive drawdngs is not to be recommended. 

Stress Sheet. The stress sheets for various structures are usually 
not made in the drafting room, but are made in the designing room 
of the company. Much data and many computations are made by 
the designer which would be of use to the draftsman in detailing. 
All of this information should be placed upon the stress sheets. 
The making of a stress sheet should be and usually is done by men 
of considerable experience. Plates I, II, V, and VI show stress 
sheets of a truss bridge, roof truss, and a pkte girder, respectively, 
and while these can not be said to be perfect, yet they indicate the 
engineering practice of our larger bridge corporations and may be 
taken for examples. (For Plates, see pages G3, 82, 88, and 89.) 



12 



STRUCTURAL DRAFTING 



ORDERING OF MATERIAL 

Since the ordering of material is of great importance it will 
be discussed here somewhat at length. Although this is usually 
done by men of considerable experience, yet it is advisable that the 
draftsman should know the method of procedure in order that he 
may be able to make the detail drawings more advisedly. 

Layout. Tyjncal Case. As has been mentioned before, the 
checker makes details to a large size scale from which he determines 




Fig. 6. Layout for Detail in Cross-Frame Connection 

the size and amount of material required for certain members. In 
order to illustrate this, let it be required to determine the size of 
the plates and the length of the angles used in the cross frame of 
the plate girder shown on Plate VL Here the checker first lays off 
the center to center of the girder to a small scale, say, 3" to 1'. These 
lines are marked 1 in Fig. 6. He next draws a web to the proper 
thickness and then follows in turn the flange angles and the bracing 
angles as indicated by the numbers 2, 3, etc., on the figure. The 
number of rivets in the top and bottom angle and in the diagonal 



STRUCTURAL DRAFTING 13 

should be given on the stress sheet. These should be laid off on the 
''layout," which is the name for the drawing that has just been made, 
any spacing, preferably 3 inches, being used so that the plate may 
be kept as small as possible. It is as a usual thing not possible to 
have the rivet spacing in both the diagonal and the top and the 
side angles of equal spacing. The number of rivets is usually put 
in the diagonal at about a 3-inch spacing, and the spacing of the 
rivets in the top and the side angles is so varied as to fill out the 
plate as indicated. No rivets should come closer to the edge of the 
plate than 1 J inches nor further from the edge than 2 inches, and no 
plate should be less than an even number of inches in width although 
its length may be in feet, or in inches to an eighth of an inch. It is 
not policy to place the length of the plate in sixteenths of an inch, 
since the shopmen are unable to cut that close. Therefore, in deter- 
mining the size of the plate the rivets should be so placed that a suf- 
ficient number should go in and the size of the plate be kept an even 
number of inches in width. If the rivets alone governed the size of 
the plate, it would be as indicated by the dotted lines in Fig. 6, and 
the dimensions would then be as indicated by the dimensions with a 
line drawn around it. The correct size of the plate is as indicated by 
the full line. 

The length of the line from intersection to intersection point 
is S'-Qtc" as indicated upon the drawing. In order to have the 
length of the diagonal to come out the nearest sixteenth of an inch, 
the distance of the first rivet from the intersection is taken arbi- 
trarily and is as indicated here, 7 inches. It is not necessary to give 
this dimension to a thirty-second of an inch, since if the diagonal 
varies that much from the computed length, it can be drawn up into 
place by using a drift pin and can be riveted up without injuring 
the material. 

Use by Checker and Draftsmen. The checker has now deter- 
mined the size of the plate and the length of the diagonal angle 
and he records them upoji the material bill which is to be sent to the 
mills as an order for material. This layout together with a copy 
of the material bill should be given to the draftsman when he starts 
to detail the girder. He will then have the size of a plate and the 
size of an angle for that particular girder so that the material which 
has been ordered,, probably months before, and has arrived before 



14 



STRUCTURAL DRAFTING 



TABLE I 
Allowances for Single Lengths 



Description of Material or Rule 



Allowance 
Inches 



Web plates when ends are planed 

Web plates when one end only is planed 

Web plates over 24" wide, ends not planed 

Web plates under 24" wide 

Cover plates and all other plates that must be full length when 

in work 
All angles where full length must be maintained 
All channels when ends are planed 
All channels when ends are not planed 
All I-beams when ends are planed 
All I-beams when ends are not planed 
All Z-bars when ends are planed 
All Z-bars when ends are not planed 

All plates over |" thick (except when ends must be planed) 
Order width of all sheared plates I" greater than finished width 

when planed edges are specified 
Order all end connection angles which must be planed or faced 

^" thicker than specified thickness 
Order sole plates planed one side re" thicker than specified 
Order sole plates planed both sides |" thicker than specified 
Order Tees when ends are not planed 



Add 



Add 



the draftsman starts the detail, can be used and will be used in that 
girder. In case the draftsman details the cross frame without con- 
sulting the layouts and bills of material, he is liable to draw up a 
detail which will demand a plate larger or smaller than that ordered 
for that particular plate; in the first case a new plate will be required, 
the ordered plate being placed in the stock pile until some other 
job comes up in w^hich it can be used; and in the second case the 
plate ordered will have to be cut dow^n to the size of plate the 
draftsman has used, thus necessitating extra expense and loss of 
material. 

In accordance with the method above stated, layouts are made, 
then material ordered for all details, and these layouts and copies 
of material bills are laid aside to be placed in the hands of the drafts- 
man who detailed the subject. Before the material is ordered from 
the mills, these bills should of course be checked by another checker 
or by the squad boss. 



STRUCTURAL DRAFTING 15 

In making layouts where angles are placed so that one of their 
legs is vertical, care should be taken to see that the horizontal leg 
is at the top in all cases where the angle is exposed to the action of 
rain and snow. If it is not in this position the angle, in case it is on 
a slant, will serve as a little trough down which the rain and melted 
snow will run into the joint at the lower end. In case the angle is 
not on a slant it forms a pocket-like arrangement so that the snow 
and ice may lodge upon it to a greater extent than if it had the 
vertical leg downward. Rust will result and the angle will, there- 
fore, deteriorate. In cases such as lower chords and diagonals of 
roof trusses, the vertical leg of the angle should extend upward, 
since here the angles are not exposed to the elements and it is some- 
what of an advantage that the angle should catch any dust which 
falls upon it, and should hold it in order to keep it from dropping to 
the floor beneath. 

Allowances for Planing and Cutting. Single Lengths. When 
material is ordered it should be so ordered that it will be sure to be 
of the correct length when it gets to the shop. If the material is 
ordered in single lengths, that is, the length ordered to go into the 
finished structure without being cut in two or more pieces after it 
gets to the shop, it is customary to make some allowance for planing 
off the ends or for chance errors in the mills where the men may not 
be careful enough in cutting and may accidentally make the cut 
a short distance on one side or the other of the mark which would 
give the exact length The customary allowances for single lengths 
are given in Table I. • 

Multiple Lengths. In cases where there are several pieces of 
the same size and length, they may, for convenience in handling, 
be ordered in one piece at the mills and cut into lengths after they 
reach the shop. In this case, however, care must be taken that the 
multiple length is not too long to ship on an ordinary freight car. 
The allowances to be made in such cases and the general rules are 
given in Table II. 

Allowances for Pin Material. In case material is ordered for 
pins, it is necessary that certain allowances be made for turning 
and for ordering in multiple. The following very general rules are 
given in Table III, 



16 STRUCTURAL DRAFTING 

TABLE 11 
Allowances for Multiple Lengths 



No. ! Rule 

I 



9 

10 

11 

12 

13 

14 
15 

16 

17 



No pieces more than 7 ft. long are to be ordered in multiple lengths 

unless under special instructions 
In arranging multiple lengths make lengths about 30 ft. and never 

exceed 32 ft. 
Never order plates over 24" wide in multiple lengths 
Never order plates |" thick in multiple lengths 
Never order channels in multiples unless specially instructed 
Never order I-beams in multiples unless specially instructed 
Never order Z-bars in multiples unless specially instructed 
Plates and shapes to be sheared to length without finishing, add 1" 

to product of length times number required 
When planed ends are required add specified amount to each piece 

multiplied and add 1" to multiple lengths so found 
Stiffeners with fillers, add I" to net length of each for planing and 

I" to multiple length so found 
Stiffeners when crimped, order same as h-b of girder angles plus 

j" for planing and add 1" to multiple length so found 
When 4 or less shapes not over 3 ft. long are ordered in multiple 

lengths, add f" to multiple and add for planing when required. 
When ordering fillers, allow |" clearance at ends when necessary, 

and add for multiple as for plates 
Make all multiples end with nearest |" 
Tees under 7 ft. long may be ordered in multiple lengths. Add 2" 

to length times number required and make longest multiple 

24 ft. 
If I-beams or channels are cut from long lengths allow loss of 3^" 

for each cut 
7"X3i" angles can be multipHed up to and including f" in thickness 



Allowances for Bending. In all cases where angles have to be 
bent, additional material is required. In such cases the following 
rules are applicable: 

(1) In the case of Fig. 7a. Figure length on e.g. Hne of angles and add 
1" for each bend when the angle of bend is not more than about 30°; add 2" 
for each bend when the angle is between 30° and 60°; over 60° ask for special 
instructions from the forge shop. 

(2) In the case of Figs. 7b and 7c. In the case of sharply curved end 
angles or when sharp bends are made near ends, add to the length figured on 
the e.g. line as follows: 3-inch angles add 4"; 4-inch angles add 5"; 5-inch 
angles add 6"; 6-inch angles add 7"; 7-inch angles add 8"; and 8-inch angles 
add 9^ 



STRUCTURAL DRAFTING 



17 



TABLE III 
Allowances for Pin Material 



No. 



Rule 



Pins up to and including 4" in diameter, add |" to finished diameter 
for turning 

Pins 4" to 6" in diameter, add |" to finished diameter for turning 

Pins over 6" in diameter, add i" to finished diameter and order them 
rough turned unless specially instructed to the contrary 

Pins up to and including 6" in diameter shall be ordered in multiple 
length of about 12 ft. Add ^" for each tool cut and 1" to mul- 
tiple length thus found 

Pins over 6" in diameter shall be ordered in single pieces and to 
exact length required 

When pins are over 4" diameter, ordered diameters must end in no 
fractions smaller than quarter inches 




Fig. 7. Illustration Showing Angle Bends 



Shop Bills. In order to facilitate the getting out of certain 
articles which are of the same general form but of different dimen- 
sions, and for convenience in tabulating information relative to 
certain material either before or after it has been assembled into 
members for structures, certain bills called ''shop" bills are used. 
These bills, which save much drafting and much letter writing, 
may be of almost any character to suit the practice of the plant. Figs. 
8 to 26 give the headings of various bills and Fig. 27 gives the head- 
ing of a bill which is used in case it becomes desirable to change an 
order which has been sent in. The lower part of Fig. 27 is suitable 
for all of the other bills. 

These bills are made on thin paper so that prints may be made 
from them and sent to the various shops concerned. A copy of each 
should also be filed in the engineer's office, and all bills of each job 
should be kept together by binding in some way. 







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Saline Bridge Company 



Order No., 



Sheet No. 




A |E 

Floor Bolts For 



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Fig. 18. Shop Bill for Floor Bolts 



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Saline Bridge Company 

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STRUCTURAL DRAFTING 



33 



OROta Assigned to 

Name of Structure 
Namf of Purchaser 

Ship to 

Ship Via 



.PLAtTT 



SHIPPING BILL 

(RIVETED WORK) 



WoRH Fabricated at 

PLAhT 




Fig. 24. Shippiug Bill 



Order no. 



Saline Bridge Company 



BRANCH 



5HEET No.... 



MAKE MARK. 



Fig. 25. Shop Bill for I-Beams 



34 



STRUCTURAL DRAFTING 



ORDER ASSIGNED To SaLINE D RIDGE CoMPANY v\ork Fabricated at 

PLAMT ...PLAflT 

NAME or STRUCTURE 

NAME or Purchaser .. 



Fig. 26. Shop Bill with Blank Space for Sketchj 



Saline Bridge Company 
Change Order 

Please Make the Following Changes 




CHANGE FROM 


TO 


ITEM 


NO 


KIND 


Size 


LENGTH 
TT, IN. , 


MARK 


SKETCH 

m 


NO 


KIMD 


size: 


LEMGTI-i 
FT. IN. 


MARK 


SKETCH 
NO 


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FINISHED SURFACES IN PIN HOLES ARt COATED WITH WHITE LEAD AND TALLOW BEFORE SHIPMENT. 
MATERIAI 

Specif. Made by i9.. 

Inspection Checked by. f9_ 

Paint in Charge of 



Fig. 27. Sheet Used for Change of Order 



STRUCTURAL DRAFTING 
DETAILING- GENERAL INSTRUCTIONS 



35 



Lettering. In order that the drawing may give the necessary 
information and that no mistakes should occur in the reading of 
the drawing by the shopmen or others, it is necessary that the letters 
and dimensions upon the drawing be made so that they are exceed- 

////// ^aof 

Fig. 28. Method of Constructing Parts of Small Arc-Line Letters 

ingly clear. In order to save time in lettering, an alphabet should 
be used that can be made quickly and easily. The alphabet which 
is known as the straight-line alphabet fulfills these conditions. It 



nt:?a 




Fig. 29. Method of Constructing Parts of Small Arc-Line Letters 

is made b}^ one of the characters or by a combination of the char- 
acters shown in Fig. 28. A study of Fig. 29 will show that the 

general scheme of this system consists of 
the oval and the straight line. 

The slant at which these letters are 
made is a very important factor in a 
drawing, the proper slant being 3 in 8, 
as shown in Fig. 30. Even a slight in- 
crease, however, will give one the im- 
pression that the letters lean too far 
forward and it will spoil the appearance 
of a drawing otherwise good. 
The height of the lower part of the letter should be equal to 
two-thirds or more of the total height. Figures should be of the 
same height as the capital letters. The total height of the small 
letters should not be less than one-tenth of an inch. This makes 




Fig. 30. Method of Constructing 
Parts of Small Arc-Line Letters 



36 STRUCTURAL DRAFTING 

the capitals three-twentieths of an inch high, not less. The reason 
for adopting this height of letters is in order that, if necessary, ordi- 
nary tracings may be reduced for publication and the letters will 
then show up clearly. Fig. 31 shows the complete alphabet and 

otcd'9 fgi 'hijk i>m>n- op qr 
SJuv'WxyjZ >I23$5678W 

I' I" 3" _/" 5" 5" 7" 15" 
8482845 16 

Fig. 31. The Completed Letter, v/ith Arrows Showing Direction of Stroke 

the numerals from 1 to 0, also several fractions. The fractions 
should never be made less than one-tenth of an inch in height for 
each of the members, and the dividing line should be horizontal, 
never slanting. Fig. 31 also shows by means of small arrows the 
direction the stroke should take when making the different letters 
and figures. 

There is a tendency to make several of the letters and figures 
as shown in Fig. 32. This tendency should be carefully avoided, 
special attention being called to the turned-up ends of the members 
of different characters. Care should be taken not to get the upper 
part of the s and the 8 larger than the lower part. If this is done 

or if the two 

P -y^ M D- J. (T^ ^ /^ /-N parts are made 

^ / L u / y^ / _ / equal the upper 

will appear to 
be much larger 

(2 J ^) h / YV '^"'^ these char- 

acters will look 

Fig. 32. Example of Poorly Constructed Letters OUt of propor- 

tion. 

The capital letters S, G, E, F, P, and R, and the figures 2 and 
5, present some difficulties. These characters are shown in Fig. 33, 
and may briefly be commented on as follows: 




STRUCTURAL DRAFTING 



37 



Letter S,. The letter S should begin at the point 1 slightly inside 
of the circumscribed parallelogram. The line should then be tangent 
to the top and should come slightly inside of the further side at point 
2. It should then cross the center line above the middle height at 
the point 3 and be tangent at point 4 and point 5 as indicated. 

Letter G. The letter G should start at the right side of the 
parallelogram and be tangent to the top, left side, and bottom as 
well as the right-hand side where it extends upward to a height of 
one-half of its total height before the horizontal line, which should 
extend one-half of the distance across the letter, is drawn. 

Letter E. The letter E presents no difficulties other than a 
central horizontal line should extend about two-thirds of the distance 




Fig. 33. Proportion and Slant of Capitals 



across the letter and should be at an elevation- of two-thirds the 
height. 

Letter F. The letter F is but a part of the letter E as indicated. 

Letters P and R. P and R are constructed on the same general 
principle. The upper part of both letters should be at least one-half 
or more of the total height, and in the case of R the lower right-hand 
stroke should not extend further than the right-hand side of the 
circumscribed parallelogram. 

Figure 2. The figure 2 is constructed by starting at the left- 
hand side of the circumscribed parallelogram and continuing tangent 
as indicated in the figure at points 2, 3, and 4. The lower part 4 — 5 



38 STRUCTURAL DRAFTING 

should in all cases be horizontal and it should never extend further 
than the right-hand side of the circumscribed parallelogram. 

Figure 5. The figure 5 should start at the point 1 and extend 
downwards one-third of the total height. The lower part of the 
figure should then be drawn, being tangent at point 3 and 4 and 
slightly curled up at 5 where it should extend a little further to the 
left of the upper part. The horizontal part 1 — 2 should not extend 
quite up to the right-hand side of the circumscribed parallelogram. 

In all cases where inch or foot sizes are employed, they should 
be made clearly and regularly and should be not less than one- 
twentieth of an inch in length. 

Letters and figures should always be mxade by beginners by 
first preparing guide lines drawn with a pencil. Even in case the 





3 








'; • .' / ;'- ; ■ / : 1 / ; : 




1 




• ' • ' ' 1 i / / / /' /' / .' / ■ .' 1 




///////////// 


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/ / / / 




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f 1 


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'ill 


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1 




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/ 1 






i ! i ' :' i ' 1 1 1 ' 1 1 1 /" / 


I 1 ' 


.'. 



Q:^ 



5 

Fig. 34. Guide Sheet for Obtaining Correct Slant in Letters 

guide lines have been drawn upon the detailed paper, it is also 
advisable to draw them upon the tracing cloth, or place under the 
cloth a sheet similar to I"ig. 34, with the lines drawn in ink, to act as 
a guide. This practice should be continued until enough skill has 
been acquired to make the letters uniform, without the assistance 
of more than a line or two. 

The only manner in which a person can become proficient in 
lettering is through practice. A piece of paper ruled up and having 
the slant of the letter placed upon it as sho^^^l in Fig. 34 will be found 
an excellent thing on \\-hich to practice lettering. Letters can not 
be made nicely and quickly as one would suppose. Care and time 
are required until the draftsman becomes proficient in this respect. 



STRUCTURAL DRAFTING 



39 



TABLE IV 
Abbreviations 



SYMBOL 


significance: 


L. or Ls. 


Angle or angles 


L or Us. 


Channel or channels 


J. oris. 


I beam or beams 


Z. or Zs. 


Zee bar or bars 


T. or Ts. 


Tee beam or beams 


PL, Pit, or Pis., Pits. 


Plate or Plates 


@ 


of 


nil 


niler 


Stiff. 


St/ffeners 


ri. or rig. 


Flange 


r. 


Rivet 


fn 


Field rivets 


s.r 


5hop rivets 


e. 


Eccentricity 


C.I. or <l 


Center line 


or <i> 


Diameter 


# 


Pound or pounds 


c. to c. or 4's 


Center to center 


Loft or La its. 


Latticed or lattices 


Lot. or Lots. 


Lateral or laterals 


o/r. 


Alternate 


M.PI. 


fvfasonry plate 


5pl. 


Splice 



Abbreviations. In the making of drawings certain abbrevia- 
tions are used in order to save time and for the sake of convenience 
in many other respects. These abbreviations together with what 
they signify are given in Table IV. They should be carefully studied 
and should be written close to the material to which they apply 
and should at least be one-sixth to one-eighth of an inch from the 
material. Never \vTite dimensions or letters so close to a line that 
they will interfere with the line. In writing dimensions at a con- 
siderable distance from the piece of material or place to which j^hey 
apply, an arrow is used to indicate their proper position. In all 
such cases the arrow head should be at the end of the line which 
points to the place to which the abbreviation or dimension applies. 



40 



STRUCTURAL DRAFTING 



Fig. 35 illustrates some cases and also shows the form which the 
arrow should take in order to present a good appearance on the 

drawing. 

Dimension and Material No- 
tation. Proper Placing, A draw- 
ing may be said to have been 
correctly dimensioned when any 
desired necessary dimensions may 
be obtained from it without it 
being required that any dimen- 
sions should be added or sub- 
tracted or divided in order to 
obtain the desired result, and 
when no unnecessary dimensions 
are upon the drawing. By nec- 
essary dimensions are meant those dimensions which are required in 
order that the material may be fabricated so that the finished struc- 




Fig. 



35. Correct Use of Arrow and Line in 
Dimensioning 



/Z a/ 4/- 



2L5 5">'3"^8 



Q — © — © — ©-^ — © 



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[d) 



Fig. 36. Examples of Arrow-Head Construction and Proper Location of Dimensions 



STRUCTURAL DRAFTING 



41 




Fig. 37. Correct Arrow Head 



ture is as desired. Dimension lines should be full, not dotted or 
dashed; guide lines, which are lines indicating the limits of the 
dimensions, should not extend 
beyond the dimension line. The 
dimvcnsions should be placed 
where possible above the line and 
should not, as mentioned before, 
touch the line at any place. Dimension lines should be far enough 
from the piece which they dimension in order that the letters and 
figures indicating the character of the material and its size may be 
placed between the dimension line and the material itself. Fig. 36a 
shows good practice and Fig. 36b poor practice. 

Arrow heads are a source of trouble and should be made with 
care if the drawing is to present a good appearance when finished. 
They should be made as indicated in Fig. 36a and Fig. 36c, and not 
as in Figs. 36b and 36d. They should not consist as indicated in the 



//' 4 



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4 at 5"= 12' 



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(c) id) 

Fig. 38. Correct and Incorrect Placing of Dimensions 

figure showing the wrong construction, of a cross or half cross of a 
straight or nearly straight line, but should have a gradual slope as 
in Fig. 37 where it is greatly exaggerated. 

Dimensions as mentioned above should be placed above the 
dimension line where possible and the material should be noted so 
as not to interfere with the dimensioning. Figs. 38a and 38b show 
good practice and Figs. 38c and 38d poor practice. Sometimes it is 
necessary to place the dimensions as in Fig. 38c and 38d but never 
place the material notation as shown in the same figures. Fig. 38b 
gives the preferable method. 



42 



STRUCTURAL DRAFTING 



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t^ 



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4 



Q Q Q ^ 



When several spaces are equal, the matter may be written as 
so many spaces at so much is equal to so much, or each space may 
be dimensioned separately as shown in Figs. 38a and 38b. In case 
the space is too small to write a single dimension in it clearly, the 
dimension may be put at one side and an arrow used to show where 
it belongs, Fig. 35. 

In writing dimensions the inches should be given as well as the 
feet, and in case the inches amount to nothing or to a fraction, a 
cipher should take the place of the inches. 

It is not necessary when all riveis are shop rivets to draw in each 
in such cases to put in the end rivets and to inidicate the spacing 
and every rivet when the spacing is the same. It is only necessary of 
those w^hich lie between but w^hich are not shown. Fig. 38b illus- 
trates this. In case of field rivets 
all rivets must be shown. No de- 
parture from this rule should be 
dl lowed. Fig. 39 is an example of 
this. It is noted in this figure that 
although the spacing of m^any of 
the rivets is the same, yet all are 
shown in their proper place. 

In placing dimensions w^here 
two or more members are detailed 
together, dimensions for the main 
member should run straight 
through from one end to the 
other. The dimensions of the 
larger member in so far as they 
are the same as the dimensions for the smaller may be used for the 
smaller member and additional or subdimensions be placed in con- 
venient places in order to complete the detailing of the smaller mem- 
ber. As an example of this see Fig. 38a where the edge distances 
and the method of detailing should be noted, and Fig. 39 also where 
the edge distances are the subdimensions. In Fig. 39 two dimen- 
sions are given at one of the ends. This illustrates two methods 
of placing the same dimension. The dimension directly under the 
line of dimensions for the main member is placed in the preferable 
way. In the placing of subdimensions great care should be taken 



T 



.^^ 



e4-e — e — Qt Q — e- 



Fig. 39. 



Correct Method of Indicating Shop 
Rivets 



STRUCTURAL DRAFTING 43 

not to make them too small or to place them so that they interfere 
with the guide lines of the main dimension. 

Notation Used. As stated before, the feet and inches should 
always be given when a multiple space is given. For example they 
should be written thus: 

5 @ 6"=3'-0'' 

2 @ 3''=0'-6'' 

7 @ 4''=2'-4'' 

In single dimensions less than 1 foot it is not necessary to state the 
for the foot, and, therefore, we have for example 4'', 6'', lU', etc., 
up to and including 12". A dash should always be placed between 
the feet and inches as shown above. Careful attention should be 
paid to this detail since the omission of the dash may cause the 
dimensions to be considered /as all feet or all inches and time and 
money will accordingly be lost. 

In material notation the following are the rules : 
For angles the number should be placed first, the angle sign 
second, the dimension of the greatest leg next, then the small leg, 
then the thickness, and then the length in feet and inches. 
For example, 

2-L6 5" x3"xi" ^ ir'-2" 

For plates the number comes first, the abbreviation next, the 
width in inches next, then the thickness in inches, and finally the 
length in feet and inches. 

For example, 

I -PI. I8"xi" x2'-4" 

For beams and channels the number is stated first, next the 
depth in inches, then the weight in pounds per foot, then the sign, 
and finally the length in feet and inches. 

For example, 

3-l2"x5l^** Is X l8'-2" 
5 -7" X 5/^ Cs x/6'-54 

Zee bars are designated by their depth and thickness. The 
number is written first, the depth next, then the thickness, then 
the sign and finally the length in feet and inches. 



/" 




39' c 5' r- 
64 JOl/S J3^ 



c 
ee 

o 

u 

c. 

> a 

u: ^ 

> 
e 
o 




^9" c: 15" 5" 



A-^ 




"1 






i 


^ 


L-1 




--J 






^ 




3or/? 5icie5 



C;^ ^ Other side 



This side 



\-A 



Both sides 



I 

:i Other Side 



This side 



gu Both sides 



\ 



^" Other-side 

% 

I, , 

vS This side 



A 

^1 /-- 9-;-^ 



* 



I 



H^ 



<i 












^ r,VWrV?»Rj»m;>! 



STRUCTURAL DRAFTING 



45 



For example, 

3-6"x §" Z^ X l4'-d" 

Bars are designated by their number, then their size, or diameter, 
and finally their length in inches. 
For example, 

3-/"o X 20'- B" 
I -f A 16'- 4f 

Rivets and Rivet Spacing. Rivets are made in various sizes 
and are spoken of according to the diameter of their shank. Thus 
a |-inch rivet is one which has its shank | inch in diameter. The 
heads of the rivets are not perfect hemispheres, being less in height 
than one half the diameter of the head. Table V gives the dimen- 
sions of rivets of various diameters and their conventional represen- 
tation in detail drawings. These dimensions are desirable on the 
drawings since they are often necessary in order to so figure the work 
that the material will not strike the heads. Rivets smaller than f 
inch are seldom used except where the size of the material requires 
it. Rivets larger than \ inch in diameter are seldom used except in 
the heaviest work; and the beginner is advised not to use them until 
he has permission from those above him in charge. 

Rivets should not be placed so close that the material between 
them is unduly injured by pushing or that the driving tool or ' 'dolly ^' 
wall interfere with one rivet when driving the other; likewise they 
should not be placed so far apart that the material between them 
will separate or open up. Unless specified otherwise in the specifica- 
tions Table VI may be taken as good practice; for f-inch, |-inch, 
and 1-inch rivets, the minimum spacing is seen to be three diameters 
of the rivet. 

TABLE VI 
Minimum Rivet Spacing 

(All dimensions given in inches) 



Size of Rivets 


1 
4 


8 


1 


i 


1 


7 

8 


1 


Minimum Spacing 
Center to Center 


1 


u 


li 


2 


^i 


^1 


^ 



46 



STRUCTURAL DRAFTING 



The maximum spacing allowable is usually sixteen times the 
thickness of the thinnest plate they go through. The minimum and 
maximum limits placed above are not to be used wherever possible. 
Few engineers consider it advisable or permit spacings less than 2^ 
inches and 3 inches, or more than 4 inches and 5 inches for J-inch 
and |-inch rivets, respectively. 

The minimum limits above refer to the center to center of 
rivets, while the maximum values refer to the distance center to 






L 



o— ^-^'-e--e— -e- 






f^" 



6' 



Gauge line 

a 



^m^. 



e e- 



-o e- 



<y- 



Gaugeline 



5 



O 



Fig. 40. Angles with Gauge Line 



center measured along the gauge line or line along which the rivets 
are placed. 

Gauge lines may be single. Fig, 40a, or double as in Fig. 40b. 
The gauge of a shape is the distance of the gauge line from a certain 
base. In the angle it is the back, in the channel it is the back, while 
in the I-beam it is the bisecting line of the web. 

The gauges for standard channels and I-beams are given in 
the handbooks of manufacturers, such as Cambria, Carnegie, etc., 

v',yyy,yyyyyyyyyyyy.yyyyyyyyy,y,,yy,y^ wMch books alsO givC thc slzC of HvCt Or 

bolt which can be used in the flange of any 
certain I-beam or channel. This does not 
mean that the size of bolt or rivet there given 



\ 



I 



^ 



must be used in the web also, in fact, f-inch 



> 



and |-inch should be used in the web, no 
matter what size is specified for the flange. 
The standard gauges for angles are given 
in Table VII. 

While a double gauge is shown for a 5-inch 
leg, it is very undesirable to use it. Do 
not use 5-inch legs with double gauge lines. Likewise, do not use 
a single-gauge line on an angle mth a 6-inch leg or more, unless 
specially told to do so by those higher in authority. 



Fig. 41. Section Showing 

Crimped Angle, Chord 

Angle, and Web 



STRUCTURAL DRAFTING 



4? 



TABLE VII 
Standard Gauges for Angles 

(All dimensions given in inches) 











1 


r- 


ri 




1 


r 




c 


1 


-J r 


1 




vj 


^h" 




1 


^ 


L 










^ 

t 


1 ^ 




^, 






i_ 


♦ 


1 


1 




M II 1 


■ 








g 






i 


Qi 1 q^ 






,9 




L 






V \ 






' L 












■ 1 






Maxi-, 






Maxi- 






Maxi- 


7 




mum 


L 




mum 


L 




mum 




9 


Ri]/er 


9 


Rivet 


y 


River 






or 3olr 






or Bolt 






or Bolt 


a 


4^ 


b 


31 


'^ 


7 

8^ 


2 


1^ 


/ 
8 


7 


4 


7 
8 


3 


fi 


7 

8 


li 


1 


1 
2 


6 


3p 


7 
8 


ei 


// 


i 


^? 


7 
8 


i 


■5 


3 


7 


?! 


// 


5 
8 


li 


i 


/ 


4 


^4 


8 


?4 


14 


5 
8 


1 


9 

/6 


/ 


L 




9i 


9e 


L 


9i 


9e 


8 




J 


3 


6* 


2r 


1 

3 


^4 


7 




2^ 


3 


J 


2. 




// 


e 

_.., 




2i 


2^ 











*When thickness is \ inch or over. 

In the spacing of rivets in crimped angles, the distance ''6", 
Fig. 41, should be IJ inches plus twice the thickness of the chord 
angles, but never less than 2 inches. 

The grip of a rivet is the length under heads after the rivet has 
been driven. The length of a rivet is the length of the shank before 
the rivet is driven. Fig. 42, 

r\ 



xy 



these lengths for various grips 
being easily found in any 
manufacturer's handbook. 

Care should be taken in 
case of castings to add | inch 
more to those values given. 

Rivets may have two full 
heads or may have one or both heads countersunk or flattened or 
any combination. Such conditions are signified by certain signs. 



Fig. 42. Rivet Before and After Driving 



48 



STRUCTURAL DRAFTING 



all of those in common use being listed in- the handbooks already 
referred to, and also shown in Table V. 

A rivet can be driven as close to a projection as one-half the 
diameter of the head plus i inch. This requires a special ''dolly". 



1 . 



The dolly generally used requires -Z)+-inch. This is about IJ 




± 



i] 



> 



inches for a |-inch rivet and about IJ inches for a f-inch; see Fig. 

43 and Table V. / In some instances a 
special gauge, that is, one other than 
given in Table VII, is used. In such 
cases care should be taken to see that 
the distance A, to the fillet, or curve 
of the angle, is sufficient, otherwise 
the dolly could not come down evenly 
and an imperfect head is the result. 
"VMien rivets are staggered, it is 
necessary to know how close they 
may be spaced in order that they 
may not be less than the minim.um 
allowed distance center to center. 
Table VIII gives the distances center 
to center of rivets for given values of 
the spacing and gauge line. The dis- 
tances below and to the right of the 
upper zigzag line are large enough for 
f-inch rivets while those below and 
to the right of the lower zigzag line are 
large enough for |-inch rivets. For 
example, if the gauge "g^^ was If 
inches, the spacing must be at least 
2 inches in order that the distance 
center to center would not be less 
than 2f inches, the rivets being | inch. If the rivets were J inch, the 
spacing must be H inches or more in order to have the distance 
center to center not less than 2i inches. These values are found by 
going down from the value If inches in the top row until a value 
equal to or just greater than the 2f or 2J inches is found, and then 
following across to the first column where required spacing is found. 



L 



Fig. 43. 



Diagram for Minimum Rivet 
Spacing 



STRUCTURAL DRAFTING 



49 



TABLE VIII 
Values Center to Center for Various Spacings 

(All dimensions in inches) 













VALUES or X FOR VARYING VALUES Of ^AND 5 


< 


K— 


VAlUtS 

or 

5 


VALUES OF o 

IncnfS (rtcfws Incnes IncWslncws ]nfheslncne5ffiaieslnfhe5licf?eslncnesfncnesincne5hcl*e5 


v 


< 


> 




1 


1 


'i 


ij 


'1 


'i 


'1 


l| 


'1 


2 


^k 


?i 


^1 


^h 




'/ 
4 


'/ 

^ 


4 




Si 
s,i 


/# 
z 

se 
s,i 
si 
si 
si 


^ 

Si 

si 
si 
si 
si 
si 
si 


s& 

Si 

si 

si 
si 

si 
si 
si 
si 
si 
sH 
41 


si 
si 

si 

si 
si 

■4 

si 
si 

sli 
SB 

3 


si 

si 
si 
si 
si 

si 

si 
sH 
sli 

5 

ii 

^i 


si 

si 
si 

si 

si 

si 
si 

sH 

5 

4l 


si 

si 
si 

si 
si 
si 
sH 

:i 

^i 


si 

SH 

si 

sH 
si 
sH 

5 

%' 
},i 
>i 

:i 

'i 


si 

sFs 

si 
sg 

3 ■ 

^i 
^i 
ii 

Ji 

3i 


1/ 


r 


h 


> 


< 

< 
5- 


> 






si 

s,i 
si 

si 

si 
si 


si 
4 


4 
si 


si 
sH 
sH 
sH 


s,i 
si 

i 


'9 




4' 


^1 


^1 


NOTE: Values belo^ or i 

tl 11 u 


'o right of upper zigzag lines are /arge enough for ^' rivets 
• " " lovver " " •' " " " /" " 



Care should also be taken that the rivets are not so close that 
there vAW not be at least V between the holes in the direction of 
the line of stress, see Fig. 43d. 

In many cases a row of rivets must be driven below another 
row and in material which is perpendicular to the material in which 
the first row is driven. Such a case is in the cover plate of a plate 
girder, or for that matter in most cases of cover plates. In such 
cases it is desirable to know what spacing must be used in order 
that the dolly will not be interfered ^ith by the rivet already driven 
in the other row. Table IX gives such information. It is to be noted 
that the value Y is the distance from the inner side of the leg of the 
angle, and is not the gauge. For example, let it be required to 
determine the minimum stagger for |-inch rivets in a SJ-inch leg 
of a 3i''X3J''Xf'' angle. The distance Y is then equal to the 
gauge of a 3-inch leg less the thickness of the angle, or 

_ 1 5// 
— 1« 



50 



STRUCTURAL DRAFTING 



TABLE IX 
Minimum Staggers 





\,a1-c- 


1 ^ ? ^ 1^ ? ,' 








=//' •■ /" •■ 


p m"^ m^ ft^y ^v^ 


^1 


( (i) li;; ' 


^ \H^ 






i)^ 




DIAMETER 

OF 
RIVETS 


VALUES OF Y 


'g 


'1 


il 


1,1 


'1 


■1 


ll 


ll 


'1 


1 >' 


'1 


i 


// 


'i 


'/ 


Ik 


,f 


7 

B 


/ 


/ 


i 


(? 





i 


// 


'i 


'i 


'i 


'i 


1 


# 


^^ 


II 
16 


/ 


i 


All dimensions in inches 



Looking along the top row the value If inches is found and 
going downward to the f-inch line of values, f inch is found to be 
the least distance that the rivet under consideration may be driven 
from the one in the other leg of the angle. 

In some cases it is possible to drive rivets opposite if the proper 
row is driven first. Thus, in the o"X.Z\"^\" angle of Fig. 44, if 
f-inch rivets in the 5-inch leg were driven first, those in the 3-inch 
leg must stagger by f inch, as figured above. Fig. 44a, but if the 
rivets in the 3-inch leg were driven first, the distance Y—?)"—\" 



^ 



■^p" 



^ 



a 



^ 



^j^ 



b 



Fig. 44. Rivet Stagger 



A__l 




^f> 



— 2%", which, being outside the values in Table IX, show that the 
rivets in the 5-inch leg may be driven with a zero stagger, or just 
opposite. 



STRUCTURAL DRAFTING 51 

Certain clauses in most specifications call attention to the fact 
that rivets must not be used in tension. While it is desirable not to 
have rivets in tension, and their use to resist tensile stresses should 
not be encouraged, yet a rivet has a distinct 
value when used in tension. Also, tests of 
a confidential nature have come under the 
author's observation, and they tend to prove 
that rivets so used show as great an efficiency 
as a turned bolt of the same diameter. 

However, the strength of such rivets 




d 



must not be assumed as being equal to a bolt Fig. 45. Drawing of 

p IT , 1 , , 1 ■ ,1 Standard Rivet 

01 equal diameter, but must be computed. 

The head of the rivet must be drawn out to full size, and the distance 
'7i," Fig. 45, determined. The value of the rivet in tension is then 
given by the formula 

.5',= 3.14 S^dh 
where >S^=the unit shearing stress; c?=the diameter of the rivet; 
and /i=the value as determined above. 

For a |-inch rivet /z = 0.45 inch and, therefore, this value of the 
rivet in tension, *S'g being taken at 10,000 pounds per square inch, is 

>S,= 3.14X10,000X1X0.45 
= 12,360 pounds 

which is seen to be considerable, and which is equal to the body of 
the rivet being strained up to 20,050 pounds per square inch. 

It is thus seen that the head more than develops the strength 
of the body of the rivet. Therefore, in figuring the amount a rivet 
should take in tension, one should multiply the area of the cross- 
section by the allowable unit stress decided upon. Since the speci- 
fications do not give this, it will be safe to use the ultimate strength 
for rivet steel with a factor of safety of 4. Since the ultimate strength 
of rivet steel should be about 50,000 pounds per square inch, this 
would make the allowable 12,500 pounds, and a J-inch rivet would 
have a value of 

^S,= 12,500X0.6013 
= 7,510 pounds 
which is less than the amount required to strain its head up to the 
maximum allowable. 



52 



STRUCTURAL DRAFTING 









TABLE X 








Rivet Spacing Multiplication Tabic 










Pitch in inches 


i 


«5 


H 


if 


i| 


H 


H n 


i| 


;? 


n 


2i 


^1 


2i 


^i 


2f 


2 1 


1 

2 


-2\ 


■2i 


•2J 


- 3 


1 

- 3i - 3J 


-31 


- 4 


• 41 


- 4^ 


-4J 


- 5 


- 5i 


- 5i 


-5J 


J 


3 


-3i 


- 3i 


-41 


-4i 


-4i 


- 6i 


-51 


- 6 


-6| 


-61 


-71 


-7i 


-7i 


-8i 


- 85 


3 


4 


'M 


- 5 


- 5i 


- 6 


-6J 


- 7 


•7i 


- 8 


-8i 


•9 


-9^ 


-10 


-10^ 


-11 


-lU 


ti 


5 


• 51 


- 6^ 


-6i 


-7^ 


- 8^ 


-81 


-91 


-10 


-101 


-Hi 


-lU 


1-Oi 


1- U 


1- 11 


1- 21 


5 


6 


-61 


• Vi 


- 8i 


• 9 


-91 


-10 i 


-lU 


1- 


1-03 


1- u 


l-2i 


1- 3 


1- 3} 


1- 41 


1- bi 


G 


7 


-71 


-8J 


•91 


-lOi 


-HI 


1-Oi 


1- Ji 


1- 2 


l-2i 


1-31 


1-41 


1- 5i 


1- 6^ 


1- 7j 


1- 8^ 


7 


8 


-9 


-10 


-11 


1- 


1- 1 


1- 2 


1- 3 


1- 4 


1- 5 


1- 6 


1- 7 


1- 8 


1-9 


1-10 


1-11 


8 


9 


•101 


-lU 


1-01 


1- \{ 


1-21 


1- 3! 


1-4| 


1- 6 


1- 75 


1- 8i 


1-91 


1-lOi 


1-111 


2-Oi 


2- IJ 


9 


10 


-lU 


1 01 


1- If 


1- 3 


1- 4^ 


1- 5^ 


1- 61 


1-8 


l-9i 


1-lOi 


1-111 


2- 1 


2-2i 


2-3i 


2- 41 


10 


11 


1-01 


1-H 


l-3i 


1-4^ 


1-51 


1- 7i 


1-81 


1-10 


1-11^ 


2-OJ 


2-2i 


2-3^ 


2- 41 


2- 6i 


2-71 


11 


12 


1- H 


1- 3 


1-41 


1- 6 


1-7^ 


1- 9 


I-IO5 


2- 


2-U 


2- 3 


2-4^ 


2-6 


2-7^ 


2-9 


2-10^ 


12 


13 


1-2| 


1- 4i 


l-5i 


1-7^ 


l-9i 


1-101 


2- Of 


2- 2 


2- 31 


2-5.^ 


2-6'r 


2-8^ 


2-10^ 


2-llf 


3- 11 


13 


14 


1- 31 


1- 6a^ 


1- 7i 


1-9 


1-lOf 


2-Oi 


2- 2i 


2- 4 


2- 51 


2-7i 


2- 9i 


2-11 


3-Oi 


3- 2^ 


3-4i 


14 


15 


1-41 


1- 61 


1-81 


1 -101 


2- 01 


2-2,^ 


2-4i 


2-6 


2-71 


2-9? 


2-111 


3- \i 


3- 31 


3- 5.^ 


3-7t 


15 


16 


1- 6 


1-8 


1-10 


2- 


2- 2 


2- 4 


2- 6 


2- 8 


2-10 


3- 


3-2 


3-4 


3-6 


3-8 


3-10 


16 


17 


l-7i 


l-9i 


1-1 If 


2- U 


2-31 


2- 51 


2-7i 


2-10 


3-01 


3-2i 


3-41 


3- 6i 


3- 81 


3-101 


4-0. 


17 


18 


l-8k 


1-10,^ 


2-01 


2- 3 


2- b{ 


2.7t 


2-91 


3-0 


3- 2i 


3-41 


3-61 


3-9 


3-1 U 


4- U 


4-3J 


IS 


19 


1-91 


l-Ul 


2- 2i 


2- 4^ 


2-6i 


2- 9,^ 


2-111 


3- 2 


3-41 


3-61 


3-9e^ 


3-1 U 


4- 11 


4- 4i 


4-6r 


19 


20 


1-lOi 


2-.1 


2-3i 


2- 6 


2- 8j 


2-11 


3- U 


3-4 


3- 6^ 


3- 9 


3-1 H 


4- 2 


4-4i 


4- 7 


4- 9t 


20 


21 


1-111 


2-2i 


2-41 


2-7^ 


2-10^ 


3-01 


3- 31 


3- 6 


3- 81' 


3-111- 


4- li 


4-4, 


4-7i 


4-9f 


5- 01 


21 


22 


2-05 


2- 3i 


2-6i 


2- 9 


2-llt 


3-2,- 


3-5i 


3-8 


3-lO^j 


4- 11 


4- 4i 


4-7 


4-91 


5- 0^ 


5- Zk 


22 


23 


2- li 


2- 41 


2- 71 


2-lOj 


3- li 


3-4i 


3- li 


3-10 


4-01 


4- 31 


4-61 


4-91 


5- 01 


5- 31 


5-6^ 


23 


24 


2- 3 


2-6 


2- 9 


3-0 


3- 3 


3- 6 


3-9 


4-0 


4- 3 


4- 6 


4-9 


5- 


5- 3 


5- 6 


5- 9 


24 


25 


2-4'- 


2- 7i 


2-101 


3- U 


3-41 


3-7J 


3-lOi 


4- 2 


4-5a^ 


4-8i 


4-111 


5-2^ 


5-51 


5-81 


5-1 U 


25 


26 


2-5i 


2-8,i 


2-llf 


3- 3 


3- 6i 


3-9^ 


4- 05 


4- 4 


4-7i 


4-101 


5- If 


5- 5 


5-8,i 


5-1 li 


6- 2J 


26 


27 


2-61 


2- 91 


3- li 


3-4i 


3-71 


3-1 li 


4-21 


4- 6 


4- 91 


5-OJ 


5-41 


5- 7s 


5-lOi 


6-2-i 


6- 51 


27 


28 


2>7i 


2-11 


3-2i 


3- 6 


3-9, 


4- 1 


4-41 


4- 8 


4-1 1-i 


5- 3 


5-6^ 


5-10 


6- li 


6-5 


6- 8i 


28 


29 


2-81 


3-Oi 


3- 31 


3-7i 


3-1 U 


4- 21 


4-61 


4-10 


5- 11 


6- 5i 


5- 8? 


6- Oi 


6- 41 


6-71 


6-1 If 


29 


30 


2-91 


3- U 


3- 5i 


3-9 


4- 01 


4- 41 


4- 8 J 


5- 


5- 3^ 


6- 7i 


5-1 li 


6- 3 


6- 6J 


6-lOi 


7-21 


30 


h 


Ji 


if 


H 


if 


i^ 


if 


i| 


2 


2^ 


«i 


H 


n 


^1 


2} 


^1 


S 
^ 




Pitch in inches 



STRUCTURAL DRAFTING 



53 





TABLE X (Continued) 
Rivet Spacing Multiplication Table 




<0 




PITC 


H IN INCHES 




111 

Q. 


3 


3i 


^i 


31 


'H 


3^- 


4 


4i 


4i 


4i 


5 


5i 


5i 


5f 


6 


1 
































1 


2 


-6 


■6i 


' -6^ 


■ 6i 


■ 7 


■ 74 


•8 


■8i 


■ 9 


■ 91 


-10 


-10^ 


-11 


■m 


1-0 


2 


3 


■9 


-91 


-9^ 


•101 


-lOi 


- llj 


1-0 


1- Of 


1- 14 


1-2,^ 


1- 3 


1- 3J 


I-4i 


1- 54 


1-6 


3 


4 


1-0 


1-0^ 


1- 1 


1- li 


1- 2 


I- 3 


1-4 


1- 5 


1- 6 


1- 7 


1- 8 


1-9 


1-10 


1-11 


2-0 


4 


5 


1-3 


l-3§ 


i- 41 


1-41 


1- 5i 


1- 6.^ 


1-8 


l-.9i 


1-10^ 


1-111 


2- 1 


2- 2i 


e-34 


2- 4| 


2-6 


5 


G 


1-6 


l-6f 


l-7i 


1- 8J 


1-9 


M04 


2-0 


2-14 


2- 3 


2-4^ 


2- 6 


2-7i 


2- 9 


2-104 


3-0 





7 


1-9 


1-9-: 


MO! 


1-lU 


2- 0^ 


2- 2i 


2-4 


2- 5f 


2-7i 


2- 9i 


2-11 


3- 0,' 


3-2i 


3-4^ 


3-6 


7 


8 


2-0 


2- 1 


2- 2 


2- 3 


2- 4 


2- 6 


2-8 


2-10 


3- 


3- 2 


3- 4 


3- 6 


3- 8 


3-10 


4-0 


8 


.9 


2-3 


2-4J 


2- 5i 


2-61 


2-71 


2- 91 


3-0 


3- 2i 


3-44 


3- 61 


3-9 


3-1 14 


4- 14 


4-31 


4-6 


9 


10 


2-6 


2-7i 


2- 8^ 


2- 91 


2-11 


3- U 


3-4 


3- 64 


3- 9 


3-114 


4- 2 


4- 4| 


4-7 


4-94 


5-0 


10 


11 


2-9 


2-lOf 


2-ll'i 


3- U 


3- 2i 


3- 5i 


3-8 


3-101 


4- li 


4- 4k 


4- 7 


4- 91 


5- 04 


5- 3i 


5-6 


11 


12 


3-0 


3- li 


3- 3 


3- 4-i 


3- 6 


3- 9 


4-0 


4- 3 


4- 6 


4- 9 


5- 


5- 3 


5- 6 


5-e 


6-0 


12 


13 


3-3 


3-41 


3- 6i 


3-71 


3- 9^ 


4- OJ 


4-4 


.4- 71 


4-104 


5- 11 


5- 5 


5-81 


5-114 


6-21 


6-6 


13 


14 


3-6 


3- 7f 


3- 9^ 


3-lU 


4- 1 


4-44 


4-8 


4-114 


5- 3 


5- 64 


5-10 


6- 14 


6- 5 


6-84 


7-0 


14 


15 


3-9 


3-101 


4- 01 


4- 21 


4- 4i 


4- 8i 


5-0 


5-31 


5-74 


5-lU 


6-3 


6- 6f 


6-104 


7-2i 


7-6 


15 


16 


4-0 


4- 3 


4- 4 


4- 6 


4- 8 


5-0 


5-4 


5- 8 


6- 


6- 4 


6- 8 


7- 


7- 4 


7- 8 


8-0 


16 


17 


4-3 


4-51 


4-7i 


4- 9^ 


4-1 U 


5- 3J 


5-8 


6-01 


6- 4-i 


6- 8f 


7- 1 


7- 51 


7-94 


8- 11 


8-6 


17 


18 


4-6 


4-81 


4-10 i 


5- OJ 


5- 3 


5-7i 


6-0 


6-4i 


6- 9 


7- 14 


7- 6 


7-104 


8-3 


8- 74 


9-0 


18 


in 


4-9 


4-111 


5- U 


5-41 


5- 6h 


5-1 U 


6-4 


6-8f 


7- It 


7- ei 


7-11 


8- 31 


8-84 


9- U 


9-6 


19 


20 


5-0 


5-2-i 


5- 5 


5-7^ 


5-10 


6- 3 


6-8 


7- 1 


7- 6 


7-11 


8- 4 


8- 9 


9- 2 


9- 7 


10-0 


20 


21 


5-3 


5-51 


5- Si 


5-lOa- 


6- U 


8- 61 


7-0 


7- 5^ 


7-10^ 


8- 3^ 


8- 9 


9-2i 


9- 7i 


10- Oi 


10-6 


21 


22 


5-6 


5- 81 


5-lU 


6- 2i 


6- 5 


6-10 i 


7-4 


7-9^ 


8- 3 


8- 84 


9- 2 


9- 74 


iO- 1 


10-64 


11-0 


22 


23 


5-9 


5-111 


6-21 


6-51 


6- 8i 


7- 2i 


7-8 


8- U 


8-74 


9- li 


9- 7 


10- Of 


10- 64 


11- 04 


11-6 


23 


24 


6-0 


6- 3 


6- 6 


6- 9 


7-0 


7- 6 


8-0 


s-e" 


9-0 


9-6 


10- 


10- 6 


11- 


11- 6 


12-0 


24 


25 


6-3 


6- 6^ 


6- Qf 


7-01 


7- 3^ 


7- 9J 


8-4 


8-lOi 


9-44 


9-101 


10- 5 


10-1 u 


11-54 


11-lU 


12-6 


25 


26 


6-6 


6-9i 


7- 0^ 


7-3f 


7- 7 


8- U 


8-8 


9-24 


9- 9 


10- 34 


10-10 


1 1 - 44 


11-11 


12- 54 


13-0 


26 


27 


6-9 


7- 01 


7- 3| 


7-7i 


7-104 


8- 5i 


9-0 


9- 61 


10- 14 


10- 8i 


11- 3 


11- 91 


12- 44 


12-1 U 


13-6 


27 


28 


7-0 


7- 3i 


7- 7 


7-104 


8- 2 


8- 9 


9-4 


9-11 


10- 6 


11- 1 


11- 8 


12- 3 


12-10 


13- 5 


14-0 


28 


29 


7-3 


7- 61 


7-10,i 


8- 11 


8- 54 


9- Of 


9-8 


10- 3^ 


10-104 


11- 5i 


12- 1 


12- 8k 


13- 34 


13-101 


14-6 


29 


30 


7-6 


7- 91 


8- li 


8- 5k 


8- 9 


9- 44 


10-0 


10- -H 


11- 3 


11-104 


12- 6 


13- 14 


13- 9 


14- 44 


15-0 


30 


JO 


3 


-n 


3i 


3i 


31 


31 


4 


^i 


M 


4§ 


5 


5i 


5| 


5| 


6 


CO 

1 




pitcj 


H IN INCHES 





54 STRUCTURAL DRAFTING 

On account of the fact that riveted heads are not driven sym- 
metrically the value of the rivet in tension is not certain, and their 
use in tension is not to be advised. Use turned bolts. 

The bearing and shearing values of rivets may be found in the 
handbooks of the various manufacturers. The values for all values 
of allowable stresses are not usually given, but by a little trouble 
almost any values may be obtained by dividing those values there 
given, or by taking a multiple of them. For example, the bearing 
value of a |-inch rivet in a i^-inch plate, unit allowable bearing 
stress 18,000 pounds, may be obtained by taking 1| times the value 
given in the 12,000-pound table, giving 6,885 pounds. 

In cases of the webs of channels or I-beams, or other thicknesses 

of metal which are not in even sixteenths of an inch, but are given 

in decimal fractions, the values may, with the help of the slide rule, 

be obtained from the tables. For example, let it be required to find 

the value of a J-inch rivet in bearing in the web of a 15''X33# channel, 

the unit-bearing stress allowed being 15,000 pounds. From Cambria, 

the thickness is seen to be 0.4, and the bearing of a |-inch rivet in 

a J-inch plate is found to be 6,563 pounds. Therefore, the value 

sought will be 

6,563 
V=——-X 0.4=5,250 pounds 
O.o 

For convenience in rivet spacing. Table X will be found con- 
venient, the value of any number of spaces of a given length being 
determined at a glance. 

Bolts, Nuts, and Washers. Bolts are made by forming a head 
on one end and cutting a thread on the other end of an iron rod. 
In such cases the body of the bolt does not represent the strength, 
but the area at the root of the threads. In the handbooks is given 
the diameter of the screw thread for any bar or bolt of given diameter, 
and from this the strength of a bolt may be calculated, once the 
allowable unit tensile stress is determined. The diameter given for 
the rod or bolt is the diameter of the upset screw end. The strength 
of the bolt is then obtained by multiplying the diameter of the screw 
at root of thread by itself, by 0.7854,* and by the allowable unit 
stress, thus 

Strength of Bolt =0.7854 di'XS 

*In some books the area at root of thread is given direct. 



STRUCTURAL DRAFTING 



55 



TABLE XI 
Standard Cast 0. Q. Washers 



(Cef) 




^ 


-- 


J 

X 

/ 


^ 






DIMENSIONS 
a-4d -hi" 

b-^d-hf 

t -d 

c = d t b" 


i I w j 




v^___^ 






DIAMETER Of 
BOLT c/ 


J 


1 


i 


/ 


1 


'i 


'i 


'i 


'^ 


'i 


2 


DIAMETER . 
a 


^J 


^i 


^i 


^l 


^i 


^i 


^J 


-5i 


^i 


7 


^J 


\N\. Of WO 
WASHERS IN Lbs. 


31 


45 


70 


113 


175 


F56 


352 


455 


610 


865 


1115 




All 


dimensions in Inches 







For example, let it be required to determine the strength of 
a IJ-inch bolt, the unit allowable stress in tension, being 18,000 
pounds per square inch. It is 

Strength of Bolt =0.7854 X 1.284^ X 18,000 ' 
= 23,350 pounds 

while if the area of the body of the bolt was used the strength would 
be 31,800, from which it is seen that in determining the strength of 
bolts care must be taken to use the diameter at the root of the thread. 

Information regarding bolts and nuts in general is given in the 
handbooks. Here the exact dimensions of the heads and nuts are 
given. In detailing it will be sufficiently accurate to assume the 
side of a square head or nut or the short diameter of a hexagonal 
head or nut as twice the diameter of the bolt, the thickness of each 
being equal to the diameter of the bolt. 

When the nut is screwed up, the bolt should extend from \ inch 
to I inch above the nut. 

Washers are of two kinds, cast and cut. The former are desig- 
nated as O. G. (pronounced Oh Gee) washers on account of the curve 
given to their side. The sizes and weights of 0. G. washers are given 
in Table XL 

Cut washers are made by stamping them out of sheet metal, 
and are principally used as separators where two angles are bolted 



56 



STRUCTURAL DRAFTING 



together, or under the heads and nuts of small bolts which bolt timber 
in place. General information regarding them is given in Table XII. 

TABLE XII 

Standard Cut Washers 

(In 200-pound kegs) 











/^ 


^v 






a -^d i-f 


1 


r^'~^\ — 


— 




c = d i- £ up to d = /' 




Qi - 




^d-f-s vvhen d 


1 


--/ 


is greater than r 






1 


SIZE OF 
BOLT OR 
UPSET=(y 


DIAMfTCR 
a 


OLAMETER 
Of 

HOLE C 


THICKNESS 
/ 


NO IN 

100 ?^m\)Z 


J 


i i 


^ 


36 200 


/ 
4 


/ 


i 


k 


4 900 


i 


/ 


i 


■ 


II 100 


i 


/ 


/ 


d 


6 700 


i - 


■4 <? 


1 4 100 


/ 

3 


'/ 1 i 


J> 


2 600 


i 


'^ 1 / 


n 


2 700 


1 


'i M 


i 


1 500 


i 


I s 


- 


1 000 


7 


H \ i \ ^^6 


1 


s^ \ 'h 


i 


595 


'S 


li \ V' 


- 


507 


U 


^ '/ 


.] 


428 


'i 


a 1 '/ 


S 


528 


'^ 


! '/ 


- 


284 


'■/ 


3} If „ ete 


'i 


' 


// 


- 


218 


'i 


-/ 


3 


- 


/94 


^ 


'^ 


H 


•.. 


,73 


\ All dimensions in inches 



STRUCTURAL DRAFTING 



57 



Tension Members. These may consist of square, round,- or 
rectangular bars, or they may be of shapes riveted together. The 
latter class will be considered under the detailing of tension members. 

When the bar is square or circular in section, it may be formed 
into loops at its ends, or upset and nuts put on, in order to attach 
it to other parts of the structure in which it is used. In the former 
case it is called a loop bar. In case it is rectangular in section it may 
be formed into a loop bar, or may have its ends forged out into a 
somewhat circular shape, see Fig. 46, and a hole bored in them in 
order to connect them to the rest of the structure. In this case it is 
called an eye bar. 

In order to be assured that the eye bar will not break in the 
head, the distances a are made such that 2a is greater than w, usually 
between 1.3w; and lAiv. If not required by the specifications, it is 
usually left to the manufacturers with the stipulation that the eye 
bars must break in the bodv of the bar, not in the head. 



<P 



K 


z 


> 




\ 








^ 




/ 
/ 


/ 







/ ^ 

Fig. 46. Dimension3 Required in Eye-Bar Design 



The dimensions of eye bars are given in the handbooks. In 
Cambria the excess through the pin hole for the 2-inch bar is (4| — 1|) 
-^2=1^, an excess of 33 per cent. 

Care should be taken to note that the values here given are the 
minimum thicknesses. Bars thinner than these are liable to upset 
so imperfectly as to be unsafe in the heads. An eye bar should not, 
as a rule, be less in thickness than one-sixth of the depth. The pins 
given in the tables in the handbooks are maximum pins. The 



c 
<a 

a 

E 

o 

*z 

CO 

c 



< 05 



w. a 

O 0) 



g5 

















<\j <n po CO 


"»9 -t»-<Vj 
CO ^ ^ q 


<3 iTi in »n 


i 


r 

1 

1 

1 
1 

1 
1 

1 
1 

s 
1 




2 

O 
ID 

a: 
o 

Q: 

UJ 

H- 

UJ 

z 
<l 
o 


cn 




f*? Od o^ Ci 

(Vj <\, (Vj f'^ 


•n "^ •<% "^ 


^ «>, vo N 
•^ -o -^ f^ 


1 


1 


1 


NKJO 




\0 K 05 CN 
r>j C\j (A^ (\j 


<5i <" <V "^ 

•«^ -^ N^ ^<^ 


\h <o vo N 
-»>) K>) r<>^ K^ 


-^ 

•^ 






^ N <xj a 

% (\j (\J (Vj 


(Cl fC> fr( -Ci 


^ N>j fCN ro, 




•moo 
CVj 




>n NO N 00 
t\j (\j (\j i\, 


(\j »'^ f<-l N^ 


•^ '!^ U> vo 
-^ -n "^ -n 


^ 


-KVj 




>n vo N 05 
(\j (\) C\j (Vj 


rvj «^ «>, ^f^ 


"0 "^ '<> -cs 




(IMCO 

CVJ 




^J. ^ VO -^ 

•Xj ^J "V <\j 


CD Oi Ci - 

% (\j "> "^ 


-^ -Ol N>, ffN 






•Xi f\. c\j 


> in vo -^ 
(Xj tV^ '\j (V, 


OQ 0> Q V 

'\j "vj «> '<^ 


^ fVj -^ ^ 
K> WN «r\ cTN 






% 


-«0 


(\, <V (X. 


^ ^ «>. VO 
(A., (\. '\. (\, 


N oa o 15) 

(\, (\) (Vj -^ 


«1K») -V >, '"(ft 
-- (Vj "? ^ 
«^ ir» fci in 






'"^ 


^ 




1 

1 

1 
1 


(M 


On <:i ^ i\j 
•^ c\i fX) cv 


«^ <* «o vo 

\, (\o (Vj f\< 


N. CO O (^ 
(\, (V, C\j 1^ 


^ •C(V,K^ 

lo, fT) r^ (o^ 


-^ 

-^ 


B 


J 1 

( 


>^ioo 


^ t\j (\i c\, 


^ ^ M- O, 

rVi fV) f\j f\i 


VO K Oo C> 
(\) (\j (\i (\j 


Ci ^ (Vj ''^ 

K>, W> -<>) «>> 




c^l^J■ 




fVj t^ 'q- ''^ 

(\j f\l (\j C\j 


(Vj f\j (\j <\j 


IO| «>j «>, w^ 




«N<D 




f\j -A M. \f 
(\j.(\ (\( f\) 


«>, VO 1^ 00 

r\j fVj (\j f\o 


(\j "O "^ "^ 




~K\j 


<0 fV Ct) Co Os Ci 

•- - - ^ ^ ^, 


(\, f\, <\, rv, 


<fN vS nT 00 
fVj <\) (Vj (Vj 


(Vg K^ K^ >f^ 


^ 


•nioo 


V^ >0 S. QO 0\ <a 

- ^ - - ^ ^ 


fv, (\) (\j f\J 


,\}. U^ VO N^ 

(\j cvi cvj ^J 


(\j t\j «> f^ 


? 


-^^ 


%. ^ ^ ^ ^ ^ ^ 


■Vj (Vj (\j (V. 


(\j IX, (Vj (A.; 


(X) <Xj '^ 1^ 


> 
n 


\ 




-TO 


-J? ^«^' vO N CO <^ 

>» -N ^ ^ >« ~« -^ 


•Aj ^j % (\j 


t\j (\j (Xj (\j 


<Xj (Xj ^J N^ 




/ 


A \ 




A^ 


- 






x^ \f TN ysr 

(Vj f\j (Xj fXj 


(\j Og (Xj ''^ 


»«^ 


fp 


^ 


1 


-SCO 




^ (Nj (\j (\, 


''^ ^j ^ iTi 
(\, (\j cvj (\, 


VO N OD 0\ 
fVj (\j (\j r\j 


*«Vj 


V! 


a 


f) 






<»)lTt 




^^?> 


(Xj kn" ^5- fN 
tCJ (V^ <X; (\j 


C^ (X, fVo^ 


o 

"^ 


</ 


















Q a. 


— -__ CVj(\j(\j(\j 


(T) ro CO ro 


•^ ^ -^ ■^ 


-.rf-KVj.-** 

in in lo ir> 


_J 



STRUCTURAL DRAFTING 59 

American Bridge Company practice requires the smallest pin to 
be not less than three-fourths the width of the eye bar. 

Bars of a square or circular section could, as in the case of 
bolts, have a screw thread cut on their ends and by means of nuts 
be connected to the other part of the structure, but such an opera- 
tion would be costly since the bars are long and much of the section 
would be wasted for a great length. In such cases the bars are ordered 
6 inches longer than required and this 6 inches is, after heating to a 
welding heat, upset or pushed in 6 inches, thus increasing the diameter 
of the bar at the end so that the diameter at the bottom of the screw 
threads will be greater than the diameter of the original bar. This 
is done so that the bar will break in the body, and not at the joint. 

The sizes of upsets for bars of various sizes are given in the 
handbooks. Let it be required to determine the size hole through 
which a l|-inch bar with upset end would pass and the nut required. 
We find opposite the 1| the value 1|, showing that the upset "Will 
be 1| inches. In another table opposite IJ is given the size and 
weight of a square nut, viz, IJ inches thick, 3 inches on the side, 
and weight 3,175 pounds. The use of square nuts is not to be 
encouraged, the hexagonal form being the better, on account of their 
lighter weight. 

Instead of the rods being fitted with nuts and threads at the^r 
ends, they may, as mentioned above, be made into loop bars. Loop 
bars are welded, and for this reason are not to be desired since welds 
are never as strong as the original. However, the loop bar has 100 
per cent excess through the pin, and in order to have an efficiency 
of 100 per cent it must have a weld with an efficiency of 50 per cert. 
Since such a weld is well within the limits of possibility, it is per- 
missible to use loop bars in highway bridges or other structures where 
the impact is not great, and in counters, since here the pins are usually 
of such a diameter that they would be too great for an eye bar of 
the section of the counter. Table XIII gives information regarding 
loop bars. They must be made of wrought iron since steel does not 
weld well. 

Clearances. It is very important that each member of a struc- 
ture fit together well in the field; and it is equally important that 
the draftsman should so detail his work that the various parts of 
any particular member should, without further cutting than the 



60 



STRUCTURAL DRAFTING 



first, fit together. Also the rivets should be so spaced and placed 

that they can be driven. 

The rivet clearances have been mentioned under ''Rivets and 

Rivet Spacing'' and will not be taken up here. It is sufficient to 

say that on the rivet clearances 
is where the novice makes the 
most of his mistakes. 

^^^lere the distance between 
the outer faces of several mem- 
bers placed together is to be com- 
puted, it is necessary, on account 
of the liability of plates to exceed 
their nominal thicknesses, and 
rivet heads their nominal height, 
to make certain allowances. The 
usual practice is: 

(1) Between eye (or loop) bars allow 
^ inch. 

(2) Between an eye( or loop) bar and 
a built-up member | inch. 



o 
o 
o 



\ 


c 

# - 




Fig. 47. 



Joint Showing Clearance between 
Members 



(3) Between two built-up members 
i inch. 



For example, suppose it was 
required to compute the distance out to out of the members shown 
in Fig. 47. The clearance would be as indicated, and the distance 
D would be : 



D 



10 
2 
= 18.485=181 inches 



2 (y + 0.4 +1 + 1+ 0.28 + i + li+^ + n) 



This value would be the grip of the pin which was used at this joint. 
The 0.4 inch and 0.28 inch in the above are the thicknesses of the 
channel webs, and the f inch is the height of a f inch rivet head. 

In the use of eye bars, it is essential to see that their heads as 
well as their bodies clear. In order to determine the dimension of a 
section for the necessary clearance, the size of the head must be 
ascertained. This is best done by drawing up the head to a large 
scale. The method of procedure is as follows: (1) Draw the circle 
representing the pinhole; (2) for the width of eye bar under con- 



STRUCTURAL DRAFTING 



61 



sideration, subtract the radius of the largest pinhole in Cambria 
for that bar from the radius of the given head and add the result to 
one-half the pinhole diameter in your particular case, thus giving 
you R, Fig. 46; (3) with the radius R describe a full circle; (4) with 





n"'% 



Fig. 48. Eye-Bar and Built-Up Member Showing Clearance Allowed 



the center of the pin as a center and a radius equal to 2 J R describe 
a couple of arcs 1, 1; (5) parallel to the bar and at a distance li R 
from it, draw two lines, 2, 2, intersecting the arcs 1, 1; and (6) with 
these intersections as centers and a radius equal to 1^ R describe the 
small arcs completing the head, see Fig. 46. 

No material should be closer to the edge of the eye-bar head 
than I inch. This clearance should always be given, see Fig. 48, 





/'■ 

A 







-^ '^ ^Z7- 



e ^^ 



o ^ o 



r-^ or more 



r g 

Fig. 49. Riveted Joints Showing Clearance Allowed 

although the clearance of J or j^g. on the side should be allowed as 
usual in case it was against a built-up member or another eye bar. 



62 



STRUCTURAL DRAFTING 



In case the head is on the interior of a channel or so as to come 
near the fillet of an angle, the J inch must be measured from the 
curve of the fillet. This | inch does not apply to the body of the 
bar, the clearance there being J inch in accordance with what follows. 
Wherever several pieces of metal are riveted to the same side 
of a plate or other member and could, theoretically, come close against 
each other, J-inch clearance is allowed for each case where the ends 
are not planed. This allows for the slight variations in length liable 
to occur when the surfaces are sheared. The members will then be 
sufficiently close together for all practical purposes. In order that 
no errors occur, the joint should be drawn up on a separate sheet 
to a scale of at least H or 2 inches to the foot in case the pieces meet 
at an angle. In case the pieces meet at right angles, the distances 
may be computed. Fig. 49 gives a few of the most common cases. 
As in the case of Fig. 49c and 49d the clear- 
ances at one end will be J inch and at the 
other end may be more, and should be, in 
order that the distances h and h shall be the 
same. (The distance from the first rivet to 
the end of the angle is usually 1} or IJ, 
generally the latter.) It must not be 
understood that the clearance is exactly 
J inch; it must be at least f inch, and may 
be more, up to f inch or | inch in order that 
the distance from the rivet to some other 
point or rivet may be in an even ^ inch or 



( 


F 


/' 


bo 




( 


r ^ 




( 


po 




( 
c 


) o 

)0 

1 — 


1 







Fig. 50. Column and Beam 
Connection Showing Clearance 



When I-beams or channels are placed as mentioned above, 
J-inch clearance or more instead of the J-inch is required, one of the 
most common cases where such clearance is required being shown 
in Fig. 50. For other clearances in beams see 'The Detailing of 
Beams," page 72. 

^^^lerever bolts, rods, upsets, or rolled bars pass through a hole 
or slot, the aperture should be | inch greater in diameter or J inch 
greater in dimensions in case there is a slot. The above is in case 
the material is rolled steel or iron. In case of a casting, J inch should 
be added to the dimensions of the member which is to pass through, 
the opening. 



.STRUCTURAL DRAFTING 



63 





z « 



STRUCTURAL DRAFTING 

PART II 



DETAILING METHODS 

Detailing of Angles. The line upon which the rivets are spaced 
is the gauge line. The standard gauges given in Table VII should 
not be departed from unless instructions are given otherwise or unless 
it is impossible to make the detail without doing so, in which cases 
a ''special" gauge is used. In deciding upon a special gauge care 
must be taken to see that the gauge line is not less than the standard 
edge and clearance distances for the rivet used. In Fig. 51 is shown 
the minimum values of these distances. 

In some cases, as in the flange of plate girders, the rivet spacing 
is determinate, but in the majority of cases this is not so. In the 
former case the spacing between certain limits should be made equrl 
to that at the lower limit. It is unwise 
and not economical to change the spa- ^ _ /4 /J 

cing every few feet. When the spa- 
cing is not determined, the rivets may 
be placed as desired, the only limi- 
tations being (1) that they can be ^T7 

driven, and (2) that they do not take Fig. 51. Minimum clearance Distances 

in Angle Detailing 

out too much section, providmg that 

the angle is in tension. Of course the limitations as to maximum and 
minimum spacings apply here, the spacing, being used from 3 inches 
to 4 or 4J inches fcr |-inch or }-inch rivets, the lower limit being 
used if possible in order to keep down the size of the connection 
plates. It is economical to make all the spaces equal. The 
spacing may be governed by the desire to have the connection plate 
symmetrical. The distance from the end of the angle to the first 
rivet is usually 1| inches for |-inch rivets, but 2 inches is sometimes, 
though seldom, used. In case two angles are used as tension 



/i" 



/i 



.^ti. 



^orff nVers 

^ J" ■ 
/or^ rivets 



66 



STRUCTURAL DRAFTING 



members, they may be riveted together at distances not greater 
than 12 to 18 inches. 

The gauge line in single gauge angles is used as the working 
line, and passes through the working points. In the case of a double- 
gauge line, the inner gauge line should be used as the line of reference 
since by so doing the stresses in the angle will be less than if the 
reference line was taken midway between the two lines. 

Angles in either tension or compression should be connected 
by both legs, otherwise the stresses due to eccentricity will cause 
the total stresses to be far above the average stress, as a usual case 
100 per cent. This should be done by a ''clip" angle, and as many 
rivets should go from the angle into the clip as go from the clip into 
the connection plate. As a usual thing it is not necessary to detail 




Fig. 52. Angle Detailing — Vertical Leg Not Shown 

the vertical leg of the clip, as the shopmen will attend to it; only 
show the heads of the rivets. Figs. 50 and 52 illustrate the principles 
mentioned above. 

The gauge should always be placed on the angle whether it is 
standard or special, but do not give the distances from the gauge 
to the edge of the leg. 

In detailing diagonals, the end distances to the working points 
should be so chosen that the length of the angle will end in an eighth 
of an inch. If anything, make the angle a little short center to center 
of end holes to accomplish this. The member can easily be drawn 
up in place by the moderate use of drift pins, this making it taut 
when riveted up in place. 

Detailing of Plates. The governing features of the detailing 
of plates are: (1) To keep the plate as small as can consistently be 



STKUCTUKAL DKAFTING 



67 



done; (2) to cut it as few times as possible in getting it into the final 
shape; (3) to have it symmetrical if possible; (4) to keep it an even 
number of inches in width; (5) to make it thick enough so that the 
number of rivets will be small and, therefore, the plate also; and (6) 
to detail it so that the rivet centers may be determined quickly and 
w^ith certain1:y. 

The plate is kept as small as possible for economical reasons, 
and for the same reason it should be cut as few times as possible, 
two cuts being the maximum and the desired number. It is usually 
more economical to leave the material on the plate than to trim it up. 
Therefore, it is important that the rivet spacing be so arranged that 
this can be done. In such cases the company is not only saved the 
labor of trimming the plate into some irregular shape, but it gets 
paid for the extra weight left on. Fig. 53a illustrates a plate poorly 




Fig. 53. Methods of Detailing Angles, (a) Poor Detailing, (b) Good Detailing 



detailed and Fig. 53b, one well detailed. In the latter the plate^ 
although somewhat larger, is of rectangular shape, and most engineers 
would prefer it to the other. 

It is not always possible to have a plate symmetrical. When 
a plate is symmetrical, the templet work, and, therefore, the cost, is 
much reduced. If they cannot be made symmetrical, the next best 
thing is to have as many as possible alike or of the same width. With 
a little thought along these lines a draftsman can save his week's wages 
for his company many a day. 

For economy's sake the plate should be in an even number of 
inches in width. Plates are not rolled in fractions of an inch except 
below 6 inches. If a plate is so detailed as to require a fraction of 
an inch in width, the next wider plate must be ordered and cut down 



68 STRUCTURAL DRAFTING 

to the required size, thus causing expense due to metal wasted and 
to labor required to get it cut to size. The length may be any dimen- 
sion, but it is best to have it in even eighths of an inch, thus 
2'-S|'' or 3'-oJ", etc. As mentioned before, the width of the plate 
must be stated in inches, not feet and inches. A plate is noted thus 
1-Pl. 18"X|"X2'-5i'' or 1-Pl. 2o"Xr'X3'-8|". 

If the stress in a member is great, the number of rivets will 
necessarily be large. In such cases the thickness of the plate may 
be made thicker than | inch in railroad, or ^ inch in highway or 
building work, and the member so arranged as to bring the rivets 
in double shear. Unless the rivets can be brought in double shear 
it is unnecessary to increase the thickness of the plate, for shear 
governs in case of a |-inch plate, and in case of a i^-inch plate the 
change to a |-inch plate does not reduce the number of rivets suf- 
ficiently to warrant it. 

A plate must also be of suiEcient section to transmit the stress 
from one member to the other. Since the area between the nvets 
is greater than that bearing upon the rivet, this is automatically 
attended to. In the case of shear along planes between members 
a difTerent condition obtains. Plere the com^putations are more or 
less involved, but the draftsman need not consider this phase of the 
design since in such cases the experienced designer will design the 
plate and it will come to him with the correct thickness marked 
upon it. 

The rectangular detailing of plates is, of course, simple. The 
rivets are, except in such cases as in the webs of plate girders, spaced 
after the manner of the spacing in angles, the same conditions gov- 
erning. The lines on which the rivets are placed are in such cases 
parallel to one of the sides of the plate and the spacing is readily 
laid off. 

WTien a diagonal row of rivets is on a plate, it may be detailed 
in two w^ays: (1) By rectangular co-ordinates; and (2) by spacing 
along a line located by a bevel. Only in exceptional cases is the first 
method, shc\Mi in Fig. 54a, to be used. 

The better way, and indeed it might be said the standard w^ay, 
is shown in Fig. 54b. This way is easier for all concerned, and, in 
case of diagonals, lends itself especially well, since the distance between 
working points of the plates at the ends can be computed, and the 



STRUCTURAL DRAFTING 



69 



rivet spacing being measured along this line gives the distance between 
the last holes on the plates by simple subtraction. 

A plate should be detailed from one edge (the working edge) 
and the working point. The various distances to the rivet holes 
are measured from these places of reference. The distance from the 
last rivet hole to the far or side edges is not given. The plate of 
course being originally laid out to a large scale — a layout — care is 
taken that if the distances measured out from the working edge or 
point are used, the last rivet will not come closer to or farther from 
the far side of the plate than is allowed by specifications. In the 











y^ 


A I 






>• 


y\y 


^ 




1 


It ^ t 


^ 


/ - / 1 


» c^' y y^ 


^ 


/ 


-^ 


ir 


^ 7 


y^^/orking po/r T 


'^ 


/ 


t ^ 


y 

■ork 


s^ / 


5 
^ 


1 


/ ^ 


X. 


y 


MD / <r 
g point ,^ ( \ 


^ 
















^ T •' ' 




^^-. 




■ 1 




'. 


-?3" 3 


' 4" 


4" 


4" 


4" 


i 


yyj' 


4" 


4" 


4" 


4" 


'I 




Fig. 54. 



Methods of Detailing Diagonal Row of Rivets, (a) Poor, (b) Good, (c) Example 
Wiiere Working Point is Not on the Plate 



case of the |-inch rivet, these limits are IJ inches for the smaller 
and 2 inches for the greater. Specifications govern this distance by 
making it a function of the thickness of the plate or of the diameter 
of the rivet; one specification requires 2 diameters of the rivet for 
the least and 8 times the thickness of the plate for the maximum, 
but not to exceed 6 inches. As a usual thing, engineers desire the 
distance to be IJ inches for f-inch rivets, both limits being the 
same, and li inches for |-inch rivets. 



70 



STRUCTURAL DRAFTING 



The working point may or may not be on the plate. In many 
cases it is not. However, the distances must be measured from the 
working point. A famiHar example of this is seen in the connection 
plates of the lateral systems of plate girders, see Fig. 54c. 

In indicating the bevel, two methods are used. One is to state 
the actual rectangular dimensions, and the other is to reduce them 
so that the larger is 12 inches and the other a proportional part. 
For example, in Fig. 55 are given four working points and the lines 
connecting them. The plates are shown in outline. The bevel may 
be represented by the full dimensions or by taking the longest side 
as 12 inches and the other as 9.41 inches, or 9i^ inches, since it is 

unnecessary to get the bevel 
closer than the nearest six- 
teenth. The value 9.41 is 
computed as follows : 

















1 


\ 




/ 




5 

/ 


« 1 


\,/l 


/ 


/ 




/ 


6'6" \/ 9f 


\ 




/ 




\ 




















6-6" 









Y 

12'' ~ 
Y = 



6'-6' 



9.4r 



Fig. 55. Method of Indicating the Bevel 



The method of indicat- 
ing the bevel in feet and 
inches is much used, but 
indicating it in inches is 
preferable, since it is suit- 
able to bench work. With 
the foot-and-inch method 
the floor of the templet 
shop has to be used in 
are advised for all work 



order to lay it out. The smaller values 
which can be worked on a bench. 

The number of rivets required in the connection plate m any 
direction must be sufficient to withstand the component of the 
main member attached to the plate. This can be easily determined 
by projecting the number of rivets in the diagonal against the line 
where the required number is to be placed. For example, let it be 
required to determine the number of rivets in the top of the plate 
in Fig. 56a, there being as shown 4 rivets in one diagonal and 3 in 
the other. Draw a diagram, as Fig. 56b, making o-l and o-2 the same 



STRUCTURAL DRAFTING 



71 



in slant as the diagonals above in 56a. Now with any scale what- 
soever lay off four divisions from o towards 1 and three divisions 
from towards 2 and project a line up from the last division mark 
to the horizontal line. Now measure o-a and o-h to the same scale 
which was used to lay off the divisions on the diagonal lines. There 
results 3.1 and 2.3 which means that 3.1 rivets are required for Si 
and 2.3 for 1S2, or a total of 5.4 or 6 rivets for both. 

It may be that the problem is as is shown in Fig. 56c. In this 
case the method of procedure is similar. Here, after drawing o-l 
to the same slant as the member above, seven spaces to any scale 
are laid off and the projection made to the top and side. The results 
show that 6 ri^^ets are required at the top and 3.2, or 4, are required 
at the side. 





Fig. 66. Methods of Determining Number of Rivets in Connection Plate 
from the Diagonal 



Other problems may be solved in a similar manner. The rivet 
spacing in the sides and tops is so arranged as to be equal and to 
fill out the plate, allowing the required edge distance. The plates 
should be kept rectangular as far as possible. 

In many cases, as in roof truss or wind bracing work, the com- 
puted number of rivets will be two or less. In such cases three rivets 
should be put in in order to have a satisfactory joint which will not 
loosen under vibrations which are liable to occur. 

Detailing of Combinations of Structural Shapes. The general 
methods to be followed are the same as those which have been given 
together with those which are exemplified in the discussions which 



72 



STRUCTURAL DRAFTING 

TABLE XIV 

Thickness of Lacing Bars 







/^ 


\ A fC 


\ A S 




^A /\ 


.V \ 


\ / 


\ A \ 


i V 


V \ ^ 






Single Lacing (r=^. =30°) 


Dou/^/e Loang l^r = §Q, ^45°) 


r 


c 


r 


C 


f 


O'-IO" 


1 " 

4 


l'-3" 


i" 


r-of 


/I" 


r-ef 


f 


l''3" 


1" 


I'-IOf 


f; 


''-5f 


7"' 
16 


2'-£f 


f 


r-d" 


i" 


Z'-6" 


/I" 


/'-/of 


1" 


e-9f 


/" 


^'_/- 


/" 


3'-/f 



follow. In general, the combinations consist of plates or other 
shapes held together by angles, lacing bars, or tie plates, the size 
and section of the angles being determined in the design since they 
are part of the section of the member itself, while the lattice bars 
and tie or batten plates are chosen in accordance with the specifica- 
tions employed. The specifications for lacing bars make their size 
a function of the distance between rivets. Table XIV gives the 
thickness of lacing bars for any distance between rivets. 

Detailing of Beams. This is for the most part done on ''Beam 
Sheets". These sheets are the size of the shop bills, 8JX14 inches, 
and have a printed heading and footing as on the shop bills. Between 
the heading and the footing are printed elevations and cross-sections 
of I-beams, as in Fig. 57, the number on a sheet varying with the 
number of dimension lines above and material below, i. e., from two 
to four. In some cases, those blank sketches are printed lengthwise 
of the sheet and then two only are placed upon a sheet. In case a 
channel is to be indicated, the draftsman blocks out one half of the 
section or end view, see Fig. 58, lower cut. 



STRUCTURAL DRAFTING 



73 



On these blank sketches the draftsman notes the rivets and 
rivet holes, puts on the connection and other angles, and shows all 
other information necessary for the complete fabrication of the 
beam ready for the structure of which it is a part. Figs. 58, 59, 
60, and 61 are beam sheets which have been filled in, and illustrate 
very nicely the general principles. 

The general rules regarding beam sketches are given in the 
following : 

In all possible cases the holes in the end connections to the wehs 
should be according to the standards given in the handbooks. If the 



Fig. 57. Method of Detailing an I-Beam on Beam Sheets 



connection is standard for that beam, no mention need be made of the 
fact, and if it is in the center of the iveb, no dimension is required, see 
Fig. 68, first view, left end. 

If the connection is not in the middle of the web, but it is standard, 
the location of its center from the bottom should be given, see Fig. 68, 
first view, right end. 

. If the connection is not standard, it must be noted and detailed as 
in Fig. 69, second vieiv, and if it icere not in the center of the web, its 
distance from the bottom should be given as in the case of the staiidard 
connection. In case there are holes in the outstanding leg, they should 
be shoivn as in Fig. 62. Where the leg against the tveb is standard and 
the outstanding leg is of the same punching, no dimensions need be shown, 
but the outstanding leg must be shoivn and the material notation of the 
angle yut on as in Fig. 69, first view, right end. 



Saline Bridge Company 
Order hcL^.<'/.<9. Sheet. Mo—A 
_5.BCo.Conrrfl803 
J:DOmOAf^.....^R^nzY^ '__.."-_-' 



Cope tol5'x50''l 




1 6'- 1" 
J'-IO?' 2-51' 4-3 f , 5-5 f 

3'-7li" "I 6'-lf I IO'-4i" 'I 



vol -^^ ^ 



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MAKE.f_-/-^_'>_^/_7_^_ /AV: _ _ MARK 5'_^fL_^56, 



I6'-9JI" 



CopeJ^o/rto^O^dO*^! 



Copeto/5x4d''l 
(p3 shown) i^^ 



5'-3.^, 



6 -B? 



5'-3i' 



5-Oh 



//-3a 




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■^i 



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/6-Zfi 



MAKE Qned2l'^5/5zlxJ6z9§'_ mark. 5:'^-ELJt43_ . 



Vf^-^ 



9''6i 




cut not chipped 



Lenathafl= 9-54 



2-12 5pec.^ 



/'-Oi' 5(a) /'-3= 6'^' 



/-2 



^ 



2^5x5:xi"x. 8'- 5? 




^1 



8" \6f \ /4(a)6'=r'-0" \4'4"-^/^lf] \ 



^E One /^'> J/5 */^ 9'-_6_L., _ m ar^ /:1 CL 



^ 



/5-2I6 



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MAKE JL-l^^^.3gTr_x/3.-iK. _ mas^^ A^1^4 fl^^- - 

^^'^F/oor Beams 



IjT 



MADEB/i!f-i?f.,9// 



Holes /'^_^''_^^-_ Checked BYli^//?j 9/: 

TB^I^§t'^9J^A^^^-^fA^^y'Ji^B-l^ Charge ofLAM/?77/y 



Kg. 58. TjTjical Beam Sheet Showing Dimensions Filled in According to Specificationa 



■ SB.Co.Contr.^md 



Saline Bridge Company 



Sheet No...^^. 



LASSIG 



._BRANCli 



3'- 5" 



5'-^r 



4-3 f 



3'-^J" 



^y 



/fW 



ji 



6'-/f 



4j:^i: 



9'-3f 



9' -4 8 



lO'-^i' 



^4^ 



3-6" 



6-^f 



3'-34 



5-1 /§" 



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Ijethack 



J'- 6x 6'x/i X 0-5' 



'W^^Qa(dQ'ki^^Cxit:i[J'iordji-jOj)y\fi,^^ 41" n._ 



••i^^ojij. iy-_p'y 



4"'n 

'4^n. 






-^3r 



'^43 ~ 



\i 



5-0" 
~4W 



4'- 3" 



rz^ 



4'-9i 



4 -6 A 



^'■^i' 



^ d bolts 



5-3" 



4'^^' 



5-0' 



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"make Or?eJ^:^_40^r_xJ4-_6:_ _ mark ^'^H.^JOJ' 
_ JL jf_ _» » 15} 4 a" 4 ^^ ri. ^3d 



14-6'^ 
'l5^4'r 



Rivets/ ^i^/^-. 



4'' Floor Beams MADE,BY.^/r.| .9// 

; Checked ^-^iLOdOsQl! 

^^BQUJJJL BLp6_ Chicago _ _ iMCHARGE ofA^S^3__ 



Fig. 59. Typical Beam Sheet Showing Dimensions Filled in According to Specifications 



Order ^oJJJJL. 
5.B.Co.Corjrr.''l806 



-(k 



Saline Bridge Company 

3Ji/ff_LER_ BRANci- 

/Z'-O" 



10^ 



I'-O' 



5-0" 



3^- 



S'O" 



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Fig. 60. Typical Beam Sheet Showing Dimensions Filled in According to Specifications 



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Fig. 61 . Typical Beam Sheet Showing Dimensions Filled in According to Specifications 



78 



STRUCTURAL DRAFTING 



When beams are on a slight bevel, it is desirable to have the bevel 
taken up in the connection angles and the holes in the iveb of the beam 





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Fig. 62. Detailing Connection P ate When There Are Holes in the 
Outstanding Leg 

at right angles to the center line. The bevel should be indicated, see 
third view, Fig. 68, right end. 

In case field connections to the web are made, as in cases where 
other beams are riveted to it, it is unnecessary to give the vertical spacing 
of the holes if the connection is standard. The horizontal distances and 
their number will designate which connection is required. 

For example, in the first view, Fig. 58, the six holes 5f-inch 
centers show this to be a standard for 12-inch beams, while the four 
holes 5i^-inch centers indicate the standard connection for a 7-inch, 
8-inch, 9-inch, or 10-inch beam. In all cases the vertical spacing 
will be 2J inches. It should be noted that in all cases of standard 
connections of 8 holes or less in a vertical row the rivet spacing is 
2 J inches, while all over 8 have a spacing of 3 inches. 



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Fig. 63, Method of Bringing Beams to the Same Level oji Main Girders 

The centers of all groups of field holes above the bottom of the beam 
should be given. 



STRUCTURAL DRAFTING 



79 



Tie rods are put in in case no beams are riveted to the webs, to keep 
the beams from lateral motion. The holes for these are 4? inches apart, 
and they are referenced as in Fig. 59, second view. 

Where two beams are 



placed close together, they 
should be connected by " sep- 
arators'' to prevent lateral 
motio7i. When such is the 
case the holes are indicated 
as shown in Fig. 60. The 
various kinds of wall anchors 
are shown in the handbooks 
and in Fig. 20. Care should 



o 



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Fig. 64. 



Method of Coping a Beam 
Top and Bottom 



he taken to provide for their connection to the beams when required. 

When beams are used in building work, it is usually required that 

either the upper or the loiver flanges of part or all of the beams be at the 

same elevation. When the girder or main beams are deep enough, the 



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Fig. 65. Methods of Coping Beams to Fit Beams of Various Heights 

2oiist top or bottom flanges may be brought to the same ekmtion as shown 
in Fig. 63 which shows a 12-inch and a 7-inch bea^^r^ The connection- 



80 



STRUCTURAL DRAFTING 



angles are in all cases arranged so that the rivets through the girder 
iceh and the smaller connection angles go through the connection of the 
larger beam also. 

In case it is desirable to have beams so as to have all their tops 
or bottoms at the same elevation, it may be accomplished by an 




NOTE.- That cut at point A extends to 
Intersection of far side of web with 
line of bevel. 



Fig. 66. Method of Cutting Flanges When a Beam is Coped on a Bevel 



operation known as "coping" the beam. By coping is meant that 
the flange is cut back for a certain distance depending on the size of 
the beam which is to join the beam under consideration and the web 
is then cut down a distance X and sloped back on a bevel of 3 inches 
in 12 inches, see Fig. 64. 

Fig. 64 shows a beam coped top and bottom to fit into another 
beam of its own depth. A beam may be coped on top only, Fig. 6oa, 
or on bottom only, Fig. 6ob. Other conditions of coping are shown 
in Fig. 65c — f, together with the ways of indicating them. Fig. 58 
shows some indicated in the beam sketches. 

When a beam is to be coped on 
a bevel, the flanges are not cut to a 
bevel, but are cut as in Fig. 66. 
The distances a and b should be 
given allowing a \-inch clearance^ 
and the portion of the beam coped 
is to be shoicn cross-hatched. This 
method of cutting to a bevel shoidd 
be used whenever possible, whether 
the beam is coped to fit another or is simply cut to a bevel. 

When a single beam or a girder formed of two beams having a cover 
plate riveted thereto is cut to a bevel, the cover plate should be sheared 
to the line of bevel and the beam should be cut as shown in Fig. 66. 




Fig. 67 



Method of Cutting an I-Beam or 
Channel to a Bevel 



STRUCTURAL DRAFTING 81 

\ 

When an \-heam of a channel is cut to a hevel across the depth, 
the cut should be made as shown in Fig. 67, and the distance ''a" should 
be given. 

Detailing of Roof Trusses. The first thing to determine in this 
respect is the outline of the outer line of the roof and the end, and 
the center depths. The chords should now be located by center lines 
corresponding to the gauge lines of the angles, or the center of g-^avity 
lines of the pieces, as the case may be. The above mentioned deter- 
minations may be obtained from the architect's drawing and from 
the stress sheet; and in many, if not most all cases, the center lines 
of the chords are shown on the stress sheet. The stress sheet may be 
an outline with the stresses and the sections on it, or it may and in 
fact should be as shown on Plate I. Here the designer, who is an 
experienced man, has show^n the general details. It now remains 
for the draftsman to draw this up so that the shopmen can make it. 
After he has finished, the results will be as shown on Plates II and 
III, which will now be discussed in detail. 

After the center lines of the chords are drawn in, the angles 
themselves should be drawn on by laying of the gauge lines on one 
side and then the other edge of the leg on the other side of the gauge 
line. After this the top chord should be divided into a certain num- 
ber of equal parts at each of which a purlin is to be placed. This done, 
lines from these points should be drawn perpendicular to the top chord 
and their points of intersection with the bottom chord should be 
noted. From the intersection of the center one with the bottom 
chord to the apex or top, a line is now drawn, and this is the center 
line of the main interior tie, or tension member. The member itself 
should now be drawn on this gauge line. After this the other members 
should be drawn in as shown. 

In order to proceed, the distances between the various points 
of intersection must be carefully computed, thus giving the remain- 
ing data necessary to compute the bevels, which should now be done. 

In order to determine the length of the members and the sizes 
of the plates, it is now necessary to take eacK point of intersection 
where any members meet at any other than a right angle and make 
a layout of that joint to some large scale, say IJ to 2 inches to the 
foot. The customary J-inch clearance should be allowed where 
there is any liability of pieces touching and, after the ends of the 



82 



STRUCTURAL DRAFTING 








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STRUCTURAL DRAFTING 85 

various angles are drawn in, the first rivet is set back If, IJ, or 1| 
inches as the sizes of the angle and of the rivet allow, and the other 
spacing is so arranged as to make the size and shape of the plate 
advantageous and economical. The distance from the first rivet 
to the intersection is measured off and noted. After the layout for 
each joint has been made and the necessary dimensions of the plates 
and the distance from each intersection to the first rivet has been 
determined, the length of each member may be computed. This is 
equal to the length, intersection to intersection, plus the sum of the 
distances from the first rivet at the ends to the end of the member, 
minus the sum of the distances from the first rivet to the nearest, 
intersection. For example, in the main interior tie Ui L2, Plate I, 
the length, intersection to intersection, is 21 '-10 J'', the distance from 
each first rivet to the end of the angle is IJ inches, and the sum of 
the distances from each first rivet to the nearest intersection is (4JH-9) 
= 13| inches, which is I'-IJ'^ The length of the member is: 

2r-ior+2 (ir)-i'-ir=2r-o'' 

At the point L2, Plate I, a field connection must be made as well 
as at Ui on account of the fact that the truss must be shipped in 
part in case the span is larger than 30 feet, the length of an ordinary 
gondola freight car. At Z2 both legs of the angle should be connected, 
the horizontal leg connection being by a plate. In case of riveted 
lateral bracing such as is used here, the connection plate may also 
be used as a splice plate, see Pis. 8, 9, and 10 in Plate III. 

At point Ui as many shop rivets are put in as there are field 
rivets required. This will keep the plate symmetrical, and will 
allow the same templets to be used for the top chord and main interior 
tie on both sides of the truss. This more than overbalances the cost 
of driving the few additional shop rivets. 

At Lo in this case the truss has been designed so that the rivets 
are symmetrical about the point of intersection and, therefore, only 
a suflicient number are required to take up the direct stress in the 
top and bottom chords. In many cases the end of a roof truss is as 
shown in Fig. 68, in which case the number of rivets ^0^X2 may be 
calculated from the equation: 

nh — Rn = 



86 



STRUCTURAL DRAFTING 



in which 71= number of rivets required; r= allowable stress on one 
rivet; 7^= the vertical reaction; p=the rivet spacing in inches; and 
g= distance shown in Fig. 68. 

The number of rivets in Lo Ui may be determined from the 
equation: 

65^1 



nh-Sn = 



V 



in which *S is the stress in Lq Ui, and ei the distance shown in 
Fig. 68. These formulas allow for the stress due to eccentricity. 
The rivet spacing p is usually taken as 3 inches, although it may be 
taken as any value permissible by the specifications. 

In the detaiUng of the lateral systems, Plate III, the same method 
of procedure as above mentioned should be followed. Care should 



C//p 
Angle 





Fig. 68. Typical Detail for the End of a 
Roof Truss 



Fig. 69. Method of Riveting Clip 
Angles for Carrying Purlins 



be exercised in making the layouts for the lateral plates so that 
sufficient clearances are allowed, both in regards to clearances between 
members and clearances in rivet driving. 

The purlins, or rafters, may be detailed directly upon the main 
sheet with the bracing or truss, or upon a beam sheet, preferably 
the latter. In Plate III they are upon the lateral sheet. These 
purlins should be riveted, not bolted to the chords of the trusses. 
In order to facilitate erection, clip angles should be riveted to the 
top chord as shown in Fig. 69 so that the purlin may be put in place 
and riveted up without having to hold it in place with ropes or chains. 



STRUCTURAL DRAFTING 87 

Also by this method the purhn may be put in place and used as sup- 
port for erection apparatus. In Plate III, the additional pair of 
holes at panel points of the top chord are for these clip angles. 

After the draftsman has finished his drawing he should care- 
fully check up all dimensions and bevels and inspect the drawing 
for errors in rivet clearances. The passing in of accurate detail 
drawings will soon result in a promotion to checker, a more 
pleasant position, but one with greater responsibilities attached. 

Detailing of Plate Girder Spans. The information which the 
draftsman has to start with is in the form of the stress sheet. This 
may be as Plate V which is the latest and most approved form, or 
it will be like Plate VI. In both cases the number of rivets for the 
lateral connections are given, but on Plate V the rivet curve for the 
spacing in the flanges is given and also the curve of the total and dead 
load shears and moments. 

As soon as a plate-girder stress sheet is turned over to the 
draftsman, he should lay it out at once and determine the exact 
location of the web splices, the stiffeners, and the cover plates and 
their lengths (if not given), should decide upon the lengths of the 
panels of the lateral bracing, and should also make layouts of the 
lateral plates, if possible, so that the material can be ordered at once 
if necessary. In making the above layout the following should be 
observed: 

(1) Be careful in locating splices to see that they come at a panel point of 
the lateral system. 

(2) Locate all splices and stiffeners with a view of keeping the rivet spacing 
as regular as possible. 

(3) Have the panels of the lateral systems equal if possible. If not, have a 
smaller one at the ends of the girder, the remainder being of equal length. 

(4) Stiffeners to which cross-frames are attached should have fillers. 

(5) The outstanding leg of stiff ener angles should have a gauge of 2f inches 
or more. This will enable the cross-frames or floor beams to be swung in 
during erection without spreading the girders. 

(6) It is always best to use as few sizes as possible for stiffeners, connection 
plates, etc., and avoid all unnecessary cutting of plates and angles. 

(7) Locate the end holes for laterals and diagonals so that they can be sheared 
by a single operation, see Fig. 70. This will, as a rule, throw the end rivet 
further back from the working point, and may increase the size of the con- 
nection plate, but it is desirable. 

(8) It is preferable to have an even number of panels in the lateral system 
since the girders can in most cases then be made symmetrical or nearly so 
about the center. 



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STRUCTURAL DRAFTING 



(9) The rivet spacing curve should be constructed if it is not given on the 
stress sheet. 

In addition to the above the following rules which apply directly 
to the detailing should be followed. They are: 

(1) The second pair of stifTeners over the ends of the bed plate shall be so 
placed that the plate will extend not less than 1 inch beyond the outstanding 
leg. 

(2) If spans are on a grade, unless otherwise specified, put the bevel in the 
bed plate or masonry plate and not in the base or sole plate, sometimes 
called the bearing plate. 

(3) In short spans, 50 feet or less, put slotted holes for anchor bolts in both 
ends of the girder. This will usually be covered by a clause in the specifi- 
cations. 

(4) In square spans show only one-half, but give main dimensions such as 
"overall" and "center to center" and lengths of cover plates for the entire 
span. 




one operation 



Incorrect, 
two operations 



Fig. 70. Method of Locating End Holes for Laterals and Diagonals so that They May be 
Sheared by a Single Operation 



(5) The girder detailed is always the far girder and is looked at from the 
inside. 

(6) If a span has no lower lateral bracing, only sufficient of the ends of the 
girder are to be shown in order that the detail of the base plate and its con- 
nection to the flange may be shown. 

(7) If the fillers become 12 to 15 inches wide, they become too heavy to be 
slipped in in the field and they should be riveted in place in the shop with 
at least two countersunk rivets. 

(8) When the ends of two girders meet on the same pier the masonry plate 
should be made continuous, that is, one plate to extend under both spans. 
Never make the base plates continuous since they could not be riveted up 
in the field. 

(9) Detail the bed (masonry) plate separately, never show it in connection 
with the base plate. 



STRUCTURAL DRAFTING 91 

At least two sheets are necessary to complete the detail draw- 
ings of any girder span, viz, (1) the Floor, Masonry, and Erection 
Plan, Plate VII, and (2) the Girders and Bracing, Plate VIII, although 
in many cases the information on this sheet is put on two sheets, 
the girder on one and the bracing on the other. The first sheet 
should show: 

(1) A cross-section of the floor. 

(2) A longitudinal view of the floor. 

(3) A side elevation of the floor. 

(4) The angle of skew and the width of the bridge seat. 

(5) The elevation of the bridge seats and the grade of base of rail. 

(6) The marking diagram. 

(7) All clearances. 

(8) Other essential information. 

In the marking diagram all members which are entirely alike 
should be given the same mark. It may be, and usually is a fact, 
that all marks can not be put on the marking diagram until the detail 
drawing is done since then and only then is it possible, especially 
with the plates, to determine all members which are alike. Only 
those members which are shipped loose are given a mark. Thus 
it is seen that while each connection plate has a mark, only the entire 
cross-frames are given one mark since the members which compose 
them are all shop-riveted together. "Other essential information" 
is seldom required. In this special case there is shown another track 
which it is proposed will be put in in the future. Another case is 
where each end of the span has a different height from the base of 
rail to the masonry. In such cases this should be shown. 

On this sheet should be shown the masonry plates, and if the 
ends are supported on cast-steel bases the height of these and also 
the dimensions of the base should be given. 

The following general rules apply to the second sheet, Plate VIIL 

(1) At the top of the sheet show a top view of the span with cross-frames, 
laterals, and their connections complete, the girders being placed at their 
proper distances apart. 

(2) Below this show the elevation of the far girder from the inside, with all 
field holes in the flanges and stiffeners indicated and blackened in. 

(3) If the span has lower lateral bracing, show below the elevation a horizontal 
section of the span just above the tops of the lower flange angles. On this 
drawing show the lower lateral bracing. 

(4) Cross-frames shall, whenever possible, be detailed on the right hand of 
the sheet in line with the elevation. The frame shall be of such a depth as 





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STRUCTURAL DRAFTING 93 

to permit it being swung into place without interfering with the heads of 
the flange-rivets in the girders. 
(5) Always use a plate, not a washer, at the intersection of the diagonals of 
cross-frame. 

The various parts of Sheet 2, Plate VIII, will now be taken up 
in detail and described and commented upon. 

The Webs. As a usual thing webs are never specified in frac- 
tions of an inch. If so, the next inch in width must be ordered and 
then after the flange angles are riveted on, the projecting portion is 
cut off — an expensive operation. Webs are ordered in even inch 
widths and the distance back to back of angles is made J inch or 
I inch greater than the width of the web plate. This is sufficient 
to prevent any irregularities in rolling from projecting above the 
flange angles. Some engineers favor the web planed down from the 
greater width and claim that the bearing of the web on the sole or 
base plate thus obtained is a great advantage. The advantage 
is slight, however, and unless specially instructed to detail it that 
way, it should not be done. The web splices should, as before men- 
tioned, be at a panel point of the lateral system. In some cases the 
web plates butt up against each other, being planed to an even bear- 
ing. In most cases, however, the ends of the webs are sheared off 
and the customary J-inch clearance is allowed. In this case the sum 
of the lengths of the webs as given is 2 (25'-f'0+23'-5i''=75'-9i", 
while the ''overall" distance is TS'-IC or J inch less, which is taken 
up by the distance between webs at the splice and by the small 
amount, | inch, which web is below the backs of the angles at the 
ends. This shows the webs to be i inch apart at the splices. It is 
unnecessary to place any dimensions or notes on the drawing calling 
attention to this fact since the shop will make this allowance unless 
instructed otherwise. In case the webs are to be close together, a 
note must be placed on the drawing at the splice, reading "Webs 
planed to even bearing." 

Web Splices, Web splices may be of two forms, viz, that as 
indicated on Plate VIII which takes shear only, and the moment 
web splice. The proper manner to detail a moment web splice is as 
shown in Fig. 71. In the simple shear splice both the splice stiffeners 
and the splice plates may and should have the same spacing as the 
intermediate stiffeners, and the rivet lines should be spaced so as to 



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Plate VIII. Detail Drawing of Girders and Bracing for Plate-Girder Span' 




75-/0 back fv iacA of ano/es 


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96 



STRUCTURAL DRAFTING 



correspond to the spacing in the flange angles. In the moment 
splice this should be done if possible, but this is seldom the case. 
However, in case of more than one splice occurring in half of the 
girder, they should all be made alike, being figured for the one with 
the greater stress. Since a splice plate is a species of filler, it should 
be given a mark so that in case of other splices occurring the mark 
and not all the dunensions should be placed upon it. 

Stiffeners. All stiffeners except the second from the end should 
have the outstanding leg on the side of the gauge line away from the 
center of the girder. As a rule, the end stiffeners should have enough 
rivets to take up the end shear, and the intermediate stiffeners should 



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Fig. 71 Method of Detailing a J^Ioment Web Splice 

have sufficient to take up the shear at that point. This would, if 
carried out, require a different number of rivets in each stiffener. 
Common practice requires that the spacing in all stiffeners should 
be the same and that this spacing should be the same as in the end 
stiffeners. In some cases, such as in heavy girders, it is not possible 
to do this on account of the large number required in the end stiffeners, 
and the rivet spacing is then made the same in all the intermediate 
stiffeners. 

The rivet spacing should not exceed 4f or 5 inches at the most 
and should be so placed that it should be symmetrical about the 
center. When the web plates are of even inch width, the | inch 



STRUCTURAL DRAFTING 



97 






}i^ 



,(^ 



N 



<> 



^ 



-^ 



o 







— ^ 



^ — ^ 



may be put into one odd space at the center in order to avoid | inch 

in the spacing. It may be necessary to put in a few more rivets than 

are computed as necessary, but the advantage gained by thus making 

the punching of the plate on the multiple punch possible, makes 

this advisable. Fig. 72 shows this method of detailing. In order to 

make the shear plate at the web 

splice efficient to some degree in 

withstanding the moment — for 

although it is not computed to 

take moment yet it does in reality 

— the rivets near the flange are 

placed close together for a few 

spaces. If the space changes after 

that, it should increase towards 

the middle of the web, except in 

such a case as Fig. 72 where the 

center space may or may not be as 

great as those on either side of it. 

In double-gauge flange angles 
the rivet in the stiffener should be 
in the inner guage line of the 
flange angle as shown, and no 
rivet should come closer than IJ 
inches to the end of a filler. 

Each like stiffener should be 
given a mark and in case others 
of the same kind both in size and 
punching occur, the mark may 
be used instead of the material 
notation and dimension. Those 
crimped will be given different 

mark even if size and punching are the same. It should be noted 
that some of the stiifener angles differ only from the fact that they 
have holes in their outer leg to which the cross-frames are con- 
nected, hence a different mark. 

The length of stiffeners listed on the drawing is the distance 
inside of flange angle legs. Without further instructions they will 
be ground by the shopmen so as to have a snug fit. 






?=Ff 



<K^ 



Fig. 72. 



Method of Detailing Web Plate 
Stiffeners 



y.> STRUCTURAL DRAFTING 

Fillers. Fillers are placed under angles that are crimped sihce 
the angles are only criniped f inch and not the entire J inch which 
is the thickness of the flange angles. The fillers are given marks for 
the same reasons and in accordance with the same rules that apply 
to stifTeners. 

Flange Angles. In case of double gauge on the 6-inch flange 
angle it is better to put the 2§-inch gauge on the inside, no matter 



■^37- 



ej 



t-. — ^ 


"^ 




4 


i 




1 


t 


3 


Q 



Fig. 73. 



r^-'Cenrer line of Girder 

Method of Detailing Rivet Spacing with Flange Angles 



what the thickness may be, since by this operation the rivets in the 
horizontal flange, providing that is a double-gauge line, may be 
more advantageously spaced on account of the fact that the required 
stagger will be less. 

The rivet spacing in the vertical leg of the flange angles should 
increase from the end towards the center and should remain the 
same, as far as possible, between any two stiffeners, any changes 
necessary being made near the stiffeners. Since a rivet must always 



STRUCTURAL DRAFTING 



99 



be in the inner gauge line at a stiffener, an even number of spaces 
must be between any two stiffener gauge lines, since the rivets must 
stagger. This brings one rivet in the center of the girder, which 
can not occur in case there is a splice at the center of the girder. The 
stagger may then be broken as in Fig. 73, the stiffener angle being 
placed as shown and the rivet spacing being symmetrical on each 
side of the center of the girder. 

Between the stiffeners at the end, the spacin^g should be the 
same as it is between the next two stiff eners. 

The spacing at any point should never exceed the computed 
spacing unless constructive reasons require it. On account of rivet- 
driving clearances, a |-inch rivet 
can not be driven any closer than 
li inches to another member. 
Therefore, rivets can not be 
driven any closer to the stiffener 
than IJ inches, see Fig. 74. For 
this particular sized stiffener, the 
minimum spacings next to it will 
be 3i inches and 2f inches as 
seen in Fig. 74. The rivet-spac- 
ing multiplication table, Table X, 
will be found very helpful in 
spacing the rivets here. 

Since the single gauge is used in the top flange and, according 
to the stress sheet, two rivet holes are taken out of each angle, it 
is possible to space the rivets in the outstanding leg and cover plates 
without reference to those in the other leg of the angle, due care 
being taken that they do not come closer than li inches to the out- 
standing stiffener leg. No special rule governs the spacing in the 
cover plates, the only requirement being those of the specifications, 
and that the number of rivets from the center of the span to the end 
of the cover plate or the number of rivets from the end of one cover 
ulate to the end of another shall be 




Fig. 74. Minimum Rivet Spacing for 
Stiffener Angles 



71= 



(net area of cover plate) s 



where n=the number required; 5= the allowable unit flange stress; 



KJO 



STRUCTURAL DRAFTING 



and r= the value of a rivet in single shear or bearing in the cover plate, 
whichever is the smaller. For the first cover plate on top of the 
flange angles this equation gives 



n = 



f'lfi X A - 2 (i-h f ^] X 10000 



6013 



= 13 



which shows the number 7S to be amply sufficient in this respect. 
A clause in most specifications requiring the maximum spacing to 
be not greater than 16 times the thinnest plate and not greater than 
6 inches, further governs the number, which would be 50 by this re- 




J-' 



Fi€. 



quirement. Most engineers, notwithstanding the specifications, re- 
quire the majority of the spacing to be within 5 inches. 

In case the spacing in the top flange b on a double^auge line, 
care must be taken to see that the minimum stagger. Table IX, is 
not \-iolated. In such cases it is customary- to place a rivet in the 
inner gauge line of one leg opposite a rivet in the outer gauge line of 
the other leg, and to do this until a stiffener interrupts, when 
spacings are made with the observance of Table IX, imtil the rivets 
can be placed opposite again. 



STRUCTURAL DRAFTING 



inl 



In order to illustrate the above principles in regard to spacing 
when double-gauge lines are used on both legs and the maximum 
spacing for any particular distance is shown by the rivet curve, an 
example will be given. Let the stiff eners and the rivet-spacing 
diagram be as in Fig. 75. This shows the allowable rivet spacing to 
be 2i inches at the second, 3i inches at the third, and 3J inches at 
the fourth stiffener, the distance between stiffeners being 6'-7i". 
Let it be required to determine the rivet spacing between the second 
and fourth stiffeners 



C. PI. l6"x§"^53'-5" Top &i Bottom 




Fig. 76. Detail Drawing Showing Determination of Rivet Spacing between Second 
and Fourth Stiffeners 



Since the stiffener angles have a 3-inch leg on the web, the 
gauge of which is If inches, and no rivet can be driven closer to the 
edge of the leg on the web or to the outstanding leg than IJ inches, 
no rivets can be driven closer to the gauge than 3 inches and 2\ 
inches on the sides of the outstanding leg and the edge of the other 
leg, respectively, see Fig. 76. Since 3 inches is the minimum distance 
it must be used at stiffener (2) notwithstanding the fact that the 
spacing diagram requires not less than 2\ inches. This leaves (6'-7J'0 
— '^" = ^'J^\" from that rivet to the one in the gauge at the top of 
stiffener (3), no attention being paid to 3 inches, the minimum dis- 
tance here, since it is less than the 3^ inches required by the diagram. 



102 STRUCTURAL DRAFTING 

An odd number of spaces must be used since the last rivet is on the 

other gauge line; and from the rivet-spacing diagram it is seen that 

the spacing can not exceed 2f inches until half way between the two 

stiffeners, and that a space or two of 3} inches would be allowed at 

stiff ener (3). 

By consulting Table X it is seen that 29 spaces at 2^ inches are 

equal to 6'-0i". Now (6'-4i'0-(6'-Oi'0 = 3f" or 15 fourths Ct), 

from which it is seen that if i inch was added to 15 of the 29 

@ 2\" , the result would be all that is desired; but this would leave 

the last space 2f inches and by Fig. 76 it is seen that it must be 

at least 3 inches. By making the last space 3 inches, which is \ 

inch, or -f greater than 2| inches, there remain 28 spaces between 

15 2 13 

rivet a and rivet h, Fig. 76, and onlv = — left. If, there- 

^ 4 4 4 

fore, I inch be added to 13 of the 2i-inch spaces, making 13 of 

2|''+i"=3f" each, the spacing will be correct. It is: 

1 space at 3" =0'-3" 
15 " ''2\"=?>'-\\" 
13 " "2i" = 2'-lli" 

1 - ^^3" =0'-3" 



Total=6'-7i" 



In a similar manner the second space between stiffeners has its 
rivet spacing determined. Here it is seen that the rivet spacing may 
start at 3J inches, can not exceed 3| inches until past the middle, 
and can have a few spaces at 3f inches at the stiffener. By Table X 
it is seen that 24 spaces at 3i inches equal 6'-6". Now (67i") — 
(6'-6") = li" or f and if one of the 24 spaces be increased \ inch and 
two of them are increased \ inch the entire f inch will be used up 
and the spacing will have been completed. It is* 



.-' Q\" 



21 spaces at 3i"=5'-Si 
2 - -3r=0'-7r 



In a similar manner almost any combination can be made to fill out 
any dimension. 



STRUCTURAL DRAFTING 103 

The rivets In the horizontal flange of the angle and the cover 
plate are, when the spacing is greater than 2f inches, placed opposite 
those in the vertical flanges as is shown in Fig. 76, since according 
to Table IX, F being (2|''— f'0=lF'> no stagger is required, and 
where the spacing is less than 2f inches it is changed so as to be 3 
inches or more. In such cases as this it is not necessary to give spac- 
ing in the cover plates, a note, ^'Spacing same as in vertical legs" 
or "Spacing same as in web" being all that is required. 

After all the spacing in the cover plates has been determined, 
it may be necessary to change it slightly in order to allow for better 
spacing in the connection plates, but it is common practice to make 
the connection plates conform to the spacing in the cover plates since 
by so doing the additional cost of templets for the horizontal legs 
of angles is saved; and although a few additional templets for con- 
nection plates may be required the saving is considerable. 

Cover Plates. The actual lengths required are given on the 
stress sheet, but when the preliminary layout is made and the material 
ordered, the plates are ordered longer in order that they will at least 
be the required length when they are on the girder. The cover plates 
should be stopped so that the last rivet is IJ inches from the end, 
and in the case of double-gauge angles this rivet must be on the outer 
gauge, see Fig. 76. The single gauge is to be recommended, pro- 
viding sufficient rivets can be gotten in. At the ends of the cover 
plates it is not necessary to give the distances to the edges. The 
dimensions should go on as in Plate VIII and Fig. 76. The material 
notation should be put on as shown, all cover plates on both top and 
bottom, which are of the same section and length, being listed at 
the top. Any plate which is special to the bottom, is listed there. 

The beginner should be careful to note that the bottom cover 
plate next to the flange angles does not run the entire length of the 
girder, and accordingly he should not run his rivet spacing in the 
bottom flange through to the end but should stop at the end of the 
cover plate. This is a common error for beginners. 

Cross Frames. The cross frames may be detailed as shown in 
Plate VIII or as shown in Fig. 77. A layout of the plates must be 
made; the working point being taken at the intersection of the angle 
gauges, as in Fig. 77, or at some point which is approximately in 
the line connecting these points, see Plate VIII. The latter method 



lu-i 



STRUCTURAL DRAFTING 



has the advantage in that it allows the point to be so chosen that 
the ends of the diagonals will be about J inch from both the stifFener 
and the top angle, thus making a smaller plate. The bevels are not 
stated on the diagonals since the dimensions are given directly. 

The end distances should be given or, if not, a note stating their 
value should be on the sheet. The distance, intersection to inter- 
section and end hole to end hole, should always be given, likewise 
the distance to the center of any group of holes. The rivet spacing 
may then be measured from these points. It was formerly customary 
to give the distance a, Fig. 77, but it is unnecessary and it is not now 




Fig. 77. Detailing of Cross Frames 

put on the drawing. Attention is called to the detailing of the 
diagonals in C. F. 1, the center line being half way between the gauges 
and a rivet placed on it at the ends. 

Rivet clearances should receive close attention. The first rivet 
in the horizontal leg of the top and bottom struts should be at least" 
li inches away from the edge of the cover plate, and it and all others 
should so stagger with those in the vertical flange that the field 
rivets may be driven. In case the frames are as in Plate VIII, the 
clearances of the rivets should be looked after and the spacing in 



STRUCTURAL DRAFTING 106 

the cover plates be so arranged as to have one rivet on the gauge of 
the angle. 

In cases where there is not a cover plate or where the cover plate 
is thin, the tie may, on account of its being notched | inch, press 
down on the rivet heads of the cross frames. This may be avoided 
either by cutting out the tie or by placing fillers as shown in Fig. 77. 
Since the tie is notched at i inch and the head of a |-inch rivet is 
f inch, then the cover plate thickness added to that of the angle must 
be at least (i+|)= IJ inches before a filler is required; and the thick- 
ness of the filler required in any case is 

where s is the sum of the thicknesses of the cover plate and flange 
angle, or flange angle alone in case there is no cover plate. Of course 
no filler is required at the bottom. All intermediate cross frames 
should be alike, and the end cross frames should be like each other. 
In Plate VIII, the angles are | inch and the first cover plate ^ 
inch, the sum being (|+ ^) = li¥ inches, w^hich is greater than 1|, 
no filler is required. 

The top angles should have their horizontal leg detailed with 
the cross frame. This wdll save many dimensions on the lateral 
systems when they are detailed. 

Lateral Systems. The lateral systems should be detailed in 
place whenever possible. 

All the panels of the lateral systems should be of the same 
length. If this is not possible, the shortest panels should be at 
the ends. It is seldom possible to make all the panels equal when 
a rolled-steel masonry plate is used. In case of the cast-steel pedestals, 
the dimensions of the top may be so chosen as to have all the panels 
of the lateral system equal. This will make the lengths of all angles 
with the same sized legs on connection plates equal. 

The angles may be detailed as shown in Plate VIII or as in Fig. 
78. In either case the distance between intersections and between 
end holes must be given. The rivet spacing is measured back from 
these reference points, being determined from the layout of the plate. 
The distance from the working point out to the first hole should be 
given. The end distance should be given or else noted somewhere 
else. The plate should, when a double-gauge line is used, be made 



106 



STRUCTURAL DRAFTING 



to take in both rows of rivets; however, as mentioned before, the 
double-gauge line should only be used when unavoidable. 

The working point should be in the center of the web and on the 
gauge line of the stiffener angle when the method used in Fig. 78 
is used, except in cases where a splice is used in the center of the 
girder, and then the intersection or working point should be at the 
center of the girder, see Fig. 73. All of the methods, Plate VIII 
and Figs. 78a and 78b, are in common use. The author prefers those 




Fig. 78. Detailing of Angles in Lateral Systems 

shown in 78b or Plate VIII. Sufficient clearance should be between 
the cross frame and stiffener, see Fig. 78b. 

Each different angle, as in the case of stiffeners, should have 
a different mark. In such cases the mark is all that is necessary 
to designate another angle exactly like it, thus much repetition in 
detailing is avoided. The lateral systems, Plate VIII, are good 
examples of the efficient use of the marking system. 

The size of the connection plates is determined from the layouts, 
the rivet spacing and clearances all being taken from the layout also. 



STRUCTURAL DRAFTING 



10] 



The edge distances of the working ends and edges are shown only 
when greater than 1| inches, and in some cases even then the plates 
are kept rectangular throughout except in the case of the smaller 
ones. Few sizes for many plates give evidence of good detailing, 
and Plate VIII exemplifies this. It might be noted that with single 
gauge lines in the cover plates, the plates can be detailed more 
economically than when the double-gauge lines are used in the angles. 
A notch must be cut in the plates to allow the stiffener angle 
to clear. This must be carefully located and detailed for each plate 
where it differs in the least, and all plates to which any one notch 
applies should be noted directly with the detail. 



■^r 



^^1 



T-^ 



M. 



/'-// 



l-d' 



^ 



51 



Hole 5 to be^^ 
bored for I J; 
anchor bolts 



Dimensions q an^ 
b to be proportioned 
^ - aeeor-ding-fo-end-y 
shear 




Fig. 79. Details of Cast-Steel Bearing 



Bearings. These may be as shown on Plate VIII and should 
be detailed in that manner, or they may consist of cast-steel pedestals 
with or without rollers, Figs. 79 and 80. The rollers may be either 
circular or segmental. In the latter case they should, in case the 
abutment or pier is liable to settle, have a tooth on each end of the 
lower plates, otherwise the movement of the girder and the move- 
ment due to the settlement of the abutment will cause the rollers 
to tilt over so far that they will not move back under movements 
due to temperature. 




Drilled holes^ 
for if e 
turned bolt sy, 



I '-8" 
Top Bearing for girders 
with d flange angles 




Top Bearing for girders *^i^ 
with 6" flange angles 
I'-ll" 




hfholps for if split bohs^ 



» » » 



» » » » » f 



y 5 



lf' 







Washer 




-^ 1 



forged Ring 
To. fit snugly over turned 
shoulder on bearings 




Wrought tiasonry Plate Pin with lomas nuts 

Fig. 80. Pin-Bearing Shoe and Rockers for Plate-Girder Bridges 



STRUCTURAL DRAFTING 



109 



Detailing of Compression Members. The first thing necessary 
is to determine the pin plates and the number of rivets required. 
This is done by a method already discussed. 

14' -8f 






18" 3"3"3" 



/£ 



i/'-ef 



^JM ^'' 



-L4"x4"xi '' abt. 9''0i' Ig. 




Fig. 81. Detail of a Two-Angle Compression Member 

The rivet clearances and also the clearances required in order 
that each member may fit in with the adjacent ones in the structure, 
should receive the most careful consideration. 

The compression members consisting of two angles riveted 
should be riveted together at distances throughout their length not 
greater than 12 inches. The clauses of the specifications relative 
to lattice bars, see Table XIV, and batten plates should be carefully 
read and followed. The dimensions necessary in compression mem- 



l4'-5' 



Wyyyj jy/' l3alf.5p5.at9"=9'-9" 3h"S3" 198 




Fig. 82. Detail of Compression Member Where Angles are Latticed 

bers of two angles are the same as those required in diagonals of 
plate girders. The spacing of the rivets which rivet the angles 
together need not be given but noted as ''Rivets spaced about 12 



110 STRUCTURAL DRAFTING 

inches centers." Fig. 81 is a detail of a two-angle compression 
member. 

When two or four angles are latticed, they should have tie plates 
at their ends unless otherwise specified. In such cases the method 
of detailing is shown in Fig. 82. The ends may or may not be alike. 
The left-hand end is the most usual method of connection. 

Compression members consisting of channels and lacing bars 
and tie plates are very common. Their design is given in Bridge 
Engineering and the clauses of the specifications cover the details. 
The pin plates should be on the inside, not the back, of the channel. 
Fig. 83 represents a typical detail of this class of member. 

Compression memxbers of cover plates and channels are used 
in light bridges. The detailing of such a class is sho^^ii by Fig. 84. 

Heavy compression mem.bers are made up of angles and plates. 
The detailing of such members requires considerable care in order 
that the clearances may be sufficient. Fig. 85 shows a top chord 
section Uo U2 of a riveted railroad bridge and fairly well represents 
the detailing of that type of member. 

Detailing of Built=Up Tension Members. The detail of these 
members is no different from the detailing of compression members 
of the same class, except that care must be taken not to reduce the 
section beyond the required amount, by taking out too many rivet 
holes. Those clauses of the specifications relating to batten or tie 
plates and lattice bars apply here as well as to compression members. 

Built-up tension members must be symmetrical about the neutral 
axis. 

Facilitation cf Erection. In detailing, it should be kept in mind 
that while there are many ways to detail a piece so that the shop 
and field will get it right, yet some of them are such that the fabrica- 
tion and the erection will be greatly facilitated if they are used. The 
rules to facilitate fabrication are the principles laid down in the 
previous pages. While experience is necessary in order that the 
erection will be facilitated by the correctly planned details of the 
draftsman, yet m.any points tending to this may be put in the form 
of rules or instructions. The following will, if attended to, tend to 
prevent delays and will facilitate erection. 

(1) The first consideration for ease and safety in erection 
should be to so arrange all details, joints, and connections that a 



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lU STRUCTURAL DRAFTING 

structure may be connected, made self-sustaining and safe in the 
shortest time possible. 

(2) Entering connections of any character should be avoided 
when possible, notably on top chords, floor beam and stringer con- 
nections, splices in girders, etc. 

(3) Wien practicable, jo^'nts should be so arranged as to 
avoid ha\'ing to put members together by entering them on end, 
as it is often impossible to get the necessary clearance in which to 
do this. 

(4) In all through spans floor connections should be so 
arranged that the floor system can be put in place after the trusses 
or girders have been erected in their final position, and vice versa, 
so that the trusses or girders can be erected after the floor system 
has been set in place. 

(5) All lateral bracing, hitch-plates, rivets in laterals, etc., 
should, as far as possible, be kept clear of the bottom of the ties, it 
being very expensive to cut out ties to clear such obstructions. 

(6) Lateral plates should be shipped loose, or bolted on, so 
that they do not project outside of the member, whenever there is 
danger of them being broken off in unloading and handling. 

(7) Loose fillers should be avoided. They should be tacked 
on \\ith rivets, countersunk where necessary. 

(8) In elevated railroad work, \'iaducts, and similar struc- 
tures, where longitudinal girders frame into cross girders, shelf 
angles should be provided on the latter. In these structures the 
expansion joints should be so arranged that the rivets connecting 
the fixed span to the cross girder can be driven after the expansion 
span is in place. 

(9) In viaducts, etc., two spans, abutting on a bent, should 
be so arranged that either span can be set in place entirely independent 
of the other. The same thing applies to girder spans of different 
depth resting on the same bent. 

(10) Holes for anchor bolts should be so arranged that the 
holes in the masonry can be drilled and the bolts put in place after 
the structure has been erected complete. In concrete masonry they 
should be set very carefully according to data furnished by the 
Bridge Company. 

(11) In structures consisting of more than one span a separate 
bed-plate should be provided for each shoe. This is particularly 
important where an old structure is to be replaced; if two shoes were 
put on one bed-plate or two spans connected on the same pin, it 



STRUCTURAL DRAFTING 115 

would necessitate removing two old spans in order to erect one new 
one. 

(12) In pin-connected spans the sections of top chords nearest 
the center should be made with at least two pinholes. On skew 
spans the chord splices should be so located that two opposite panels 
can be erected without moving the traveler. 

(13) Tie plates should be kept far enough away from the 
joints, and enough rivets should be countersunk inside the chord, 
to allow of eye bars and other members being easily set in place. 

(14) Posts with channels or angles turned out and notched 
at the ends should, whenever possible, be avoided. 

In conclusion, it may be said that the author has written this 
treatise with the idea of preventing the beginner from falling into 
the more common errors of judgment, as well as helping him to become 
proficient in detailing according to good common practice. 



INDEX 



J^ . PAGE 

Angles 65 

B 

Beams. 72 

Built-up tension members 112 

C 

Compression members Ill 

D 

Detailing (general instructions) 35 

abbreviations 39 

bolts, nuts, and washers 54 

clearances 59 

dimension and material notation 40 

rivets and rivet spacing 45 

Detailing, methods of 65 

angles 65 

beams 72 

built-up tension members 112 

combinations of structural shapes . 71 

compression members Ill 

facilitation of erection 112 

plate girder spans 87 

plates 66 

roof trusses 81 

Drafting materials 6 

Drafting room equipment and practice 1 

assignment of work 3 

classification of drawings 1 

materials 6 

ordering of material 12 

allowances for bending 16 

allowances for pin material 15 

allowances for planing and cutting 15 

layout 12 

shop bills 17 

personnel 2 

records 4 

stress sheet. 11 

M 

Materials 6 



2 INDEX 

P PAGE 

Plate girder spans 87 

Plates 66 

R 

Records 4 

Rivets and rivet spacing 45 

Roof trusses 81 

S 

Stress sheet 11 

Structural drafting 

detailing (general instructions) 35 

detailing methods 65 

drafting room equipment and practice 1 

T 

Table 

abbreviations 39 

allowances for multiple lengths 16 

allowances for pin material 17 

allowances for single lengths 14 

angles, standard gauges for 47 

loop bars 58 

O. G. washers, standard cast 55 

rivet spacing, minimum 45 

rivet spacing multiplication table 52, 53 

rivets, dimensions and conventional representation of . . . . 44 

spacings, values center to, center for various 49 

staggers, minimum 50 

thickness of lacing bars 72 

W 

Work, assignment of 3 



